CN104243872B - The constant current of low-power consumption and backlight control circuit and television set - Google Patents
The constant current of low-power consumption and backlight control circuit and television set Download PDFInfo
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- CN104243872B CN104243872B CN201410475543.9A CN201410475543A CN104243872B CN 104243872 B CN104243872 B CN 104243872B CN 201410475543 A CN201410475543 A CN 201410475543A CN 104243872 B CN104243872 B CN 104243872B
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Abstract
Constant current and backlight control circuit the invention discloses a kind of low-power consumption, including front end power circuit and rear end linear constant current circuit；Front end power circuit includes power supply circuit and feedback adjustment circuit；Rear end linear constant current circuit is equipped with a connection reference signal input terminal to access constant current reference voltage, and according to the size ON/OFF rear end linear constant current circuit of constant current reference voltage and the connection of LED light string；In rear end, linear constant current circuit and LED light string junction draw voltage acquisition output terminal all the way by voltage detecting circuit and, to gather the voltage of the junction, and adjust according to collection result the magnitude of voltage of control signal input, and voltage detecting circuit is used for：When detecting that rear end linear constant current circuit is turned on the connection of LED light string, conducting voltage collection output terminal and the connection of the junction；When the connection for detecting rear end linear constant current circuit and LED light string disconnects, off voltage collection output terminal and the connection of the junction.
Description
Technical field
The present invention relates to power supply control technology field, more particularly to a kind of constant current of low-power consumption and backlight control circuit and tool
There are the constant current of the low-power consumption and the television set of backlight control circuit.
Background technology
Linear constant-current modulation circuit is widely used a kind of element circuit in Analogous Integrated Electronic Circuits, is had in practice wide
General application.Wherein, in the power supply control technology field of LED television, front-end circuit output constant pressure, rear end electricity are often utilized
Boosting or decompression constant current are realized to realize the power supply to TV SKD and LED backlight in road.
In integration process is carried out to television components, TV SKD and backlight lamp bar usually require to form a complete production network, and
The different backlight LED light bars of quantity will need linear constant-current modulation circuit adaptability to export different magnitudes of voltage.In the prior art
Using a backfeed loop being connected with TV SKD power supply output terminal, the voltage of timely monitoring television main board power supply output terminal
Change.
As shown in Figure 1, it is a kind of schematic diagram for linear constant-current modulation circuit that the prior art provides.When main board power supply exports
During the output voltage rise at end, voltage-stabiliser tube TL431 is linked into by the voltage signal after resistance RB135 and resistance RB134 partial pressures
Reference input R0 in, and the voltage signal is made comparisons with the reference voltage (such as 2.5V) inside voltage-stabiliser tube TL431,
So that voltage reduces between voltage-stabiliser tube TL431 anode and cathodes, and then the electric current of optocoupler diode PCB101A becomes larger, collector and hair
Dynamic electric resistor between emitter-base bandgap grading diminishes, and the voltage between collector and emitter is lower, therewith the inside transformation in power supply circuit
Device output voltage is reduced to the voltage of setting.Therefore, as the increase of resistance RB134 resistance values, LED power supply output terminals and mainboard supply
The output voltage at electricity output end reduces, otherwise voltage rise.
Due to the difference of application scenario, linear constant current circuit is generally required in the actual production process and exports different voltage
Value, and the prior art is in order to meet different occasion needs, it is necessary to be adjusted to the resistance value of the resistance RB135 in hardware circuit.
Therefore, the prior art there are trivial operations, precision is low, power consumption is high and it is of high cost the defects of.In addition, in practical applications, backlight
LED light bar is in series by multiple LED, and is controlled by the switching tube of metal-oxide-semiconductor or triode to adjust the electricity of LED light string
Stream is kept constant.After linear constant current circuit works, switching tube both end voltage can be because of LED light string voltage error (general list LED
Scope is 2.8~3.4, due to more of series connection, so the difference of the upper and lower bound of the voltage range of LED light string can be bigger),
Influenced due to the intermodulation (general range 7%) of transformer, voltage more high power consumption is bigger, this can cause the cost increase of device
With the reduction of circuit efficiency.In addition, in order to reduce the temperature of switching tube, general switching tube can be managed by multiple mos or triode simultaneously
Connection uses, and which results in the increase of cost.
In addition, the prior art when being improved to linear constant current circuit, often causes the power supply in shut-off backlight LED
When, one end of backlight LED is still connected with electricity consumption device and there are weak current so that the weak current is played a reversed role to backlight LED
So that backlight LED is turned on and sent faint light, this does not allow in television set manufacturing technology field.
The content of the invention
Constant current and backlight control circuit the technical problem to be solved by the invention is to provide a kind of low-power consumption, adaptively
The magnitude of voltage of ground adjustment LED power supply output terminals, without being adjusted to hardware circuit, and can prevent when LED backlight from closing still
The phenomenon of glimmer.
To solve above technical problem, the present invention provides
A kind of constant current of low-power consumption and backlight control circuit, it is characterised in that including：Front end power circuit and rear end are linear
Constant-current circuit；
The front end power circuit includes power supply circuit and feedback adjustment circuit；It is defeated that the power supply circuit includes the first power supply
Outlet, the second power supply output terminal and feedback control end；The feedback adjustment circuit includes feedback input end, control signal input
And feedback signal output；The feedback input end with described second power supply output terminal be connected, the feedback signal output and
The power supply circuit connection；The feedback adjustment circuit is defeated to the feedback according to the magnitude of voltage of the control signal input
Enter to hold received signal to be adjusted to export feedback signal to the power supply circuit, so as to control the power supply circuit to described
The magnitude of voltage of first power supply output terminal and the second power supply output terminal is adjusted；
The rear end linear constant current circuit is connected with the cathode of LED light string to be powered, for controlling output to the LED light
The electric current of string is constant current signal；The anode of the LED light string to be powered is connected with the described first power supply output terminal；
The rear end linear constant current circuit is equipped with a connection reference signal input terminal to access constant current reference voltage, and according to
The connection of rear end linear constant current circuit described in the size ON/OFF of the constant current reference voltage and the LED light string to be powered；
Linear constant-current circuit draws one with the LED light string junction to be powered by voltage detecting circuit in the rear
Road voltage acquisition output terminal adjusts according to collection result the electricity of the control signal input to gather the voltage of the junction
Pressure value；
The voltage detecting circuit is used for：When detecting the rear end linear constant current circuit and the LED light string to be powered
Connection conducting when, turn on the connection of the voltage acquisition output terminal and the junction；When detecting the rear end linear constant current
When circuit and the connection of the LED light string to be powered disconnect, the connection of the voltage acquisition output terminal and the junction is disconnected.
Preferably, the voltage detecting circuit includes diode and pull-up resistor, and the cathode of the diode is connected to institute
The cathode of LED light string is stated, anode is connected to one end of pull-up resistor, the other end access high level of pull-up resistor；Two pole
The anode of pipe connects the voltage acquisition output terminal.
Preferably, the anode of the diode also connects the voltage acquisition output terminal by a resistance.
Preferably, the anode of the diode also connects the voltage acquisition output terminal by another diode；It is described another
The anode of one diode is connected with the anode of the diode；The cathode of another diode is exported as the voltage acquisition
End.
Preferably, the voltage detecting circuit includes a switching tube (QB3), the input terminal connection of the switching tube (QB3)
The junction, output terminal connect the voltage acquisition output terminal, and control terminal connects a Regulate signal input terminal, by described in adjusting
The magnitude of voltage of Regulate signal input terminal, makes the rear end linear constant current circuit and the connection conducting of the LED light string to be powered
Simultaneous Switching pipe (QB3) turns on, and the connection of the rear end linear constant current circuit and the LED light string to be powered is opened while disconnection
Close pipe (QB3) cut-off.
Preferably, the voltage detecting circuit further includes resistance (RB19) and resistance (RB20)；
The output terminal of the switching tube (QB3) is connected with one end of resistance (RB19), the other end conduct of resistance (RB19)
The voltage acquisition output end voltage gathers output terminal；The control terminal of the switching tube (QB3) connects with one end of resistance (RB20)
Connect, the other end of resistance (RB20) is as the Regulate signal input terminal.
Preferably, the voltage detecting circuit further includes a switching tube (QB4), resistance (R21), resistance (RB22) and resistance
(RB23)；Wherein, one end of resistance R21 is connected on the junction, and the other end is connected to the company of switching tube QB3 and resistance RB20
On contact；
The output terminal of the switching tube (QB4) connects the other end of the resistance (RB20)；The input terminal of switching tube (QB4)
It is connected to ground；The control terminal of switching tube (QB4) is on the one hand connected to ground by resistance (RB22), on the other hand connects resistance
(RB23) one end, the other end of resistance (RB23) is as the Regulate signal input terminal.
Preferably, the switching tube (QB3) is triode or field-effect tube.
Preferably, the switching tube (QB4) is triode or field-effect tube.
Preferably, the voltage detecting circuit further includes a filter circuit of pressure-stabilizing；The filter circuit of pressure-stabilizing is connected to institute
State between voltage acquisition output terminal and ground；
The filter circuit of pressure-stabilizing includes zener diode, filter capacitor and filter resistance in parallel；And the voltage stabilizing two
The cathode of pole pipe is connected on the voltage acquisition output terminal, the plus earth of the zener diode.
Preferably, the rear end linear constant current circuit includes comparing adjustment circuit and constant-current control circuit；The constant current control
Circuit processed includes at least a switching tube (QB1) and control circuit module；The relatively adjustment circuit includes operational amplifier, described
The reverse input end of operational amplifier connects the reference signal input terminal, and positive input connection is connect by constant current detection resistance
Ground, the output terminal of the operational amplifier connect the control terminal of the switching tube (QB1) by the control circuit module；It is described
The input terminal of switching tube (QB1) is connected with the cathode of the LED light string to be powered, and the output terminal of the switching tube (QB1) passes through
The constant current detection resistance ground connection.
Preferably, when the switching tube (QB1) is triode, the collector of the triode and the LED to be powered
One end connection of lamp string, emitter is grounded by the constant current detection resistance, base stage by the control circuit module with it is described
The output terminal connection of operational amplifier；
When the switching tube (QB1) is field-effect transistor, the drain electrode of the field-effect transistor with it is described to be powered
One end connection of LED light string, source electrode is grounded by the constant current detection resistance, grid by the control circuit module with it is described
The output terminal of operational amplifier.
Preferably, the constant current detection resistance is mainly by resistance (RB6), resistance (RB7), resistance (RB8) and resistance (RB9)
Parallel connection is formed.
Preferably, the normal phase input end of the operational amplifier is connected by resistance (RB5) with the constant current detection resistance,
The output terminal of the switching tube is connected to the junction of the resistance (RB5) and the constant current detection resistance.
Preferably, the normal phase input end of the operational amplifier is also grounded by capacitance (CB5).
Preferably, the relatively adjustment circuit further includes a clamp diode；
The minus earth of the clamp diode；The anode of the clamp diode and the output terminal of the switching tube connect
Connect.
Preferably, the voltage of the junction only collected when the voltage acquisition output terminal is greater than or equal to default threshold
During value, the magnitude of voltage of the control signal input is just adjusted, so as to further adjust the first power supply output terminal, the second confession
The output voltage at electricity output end, so that the voltage of the junction is less than default threshold value.
Preferably, a control master chip is further included；
The control master chip and the control signal input, the reference signal input terminal and the voltage acquisition
Output terminal connects respectively；
The control master chip adjusts the output to the control signal according to the voltage change of the voltage acquisition output terminal
The signal magnitude of input terminal, to control the output of the first of the front end power circuit the power supply output terminal, the second power supply output terminal
Magnitude of voltage；And the constant current reference voltage is inputted to the rear end linear constant current circuit by the reference signal input terminal.
Preferably, a control master chip is further included；
The control master chip and the control signal input, the reference signal input terminal, the voltage acquisition are defeated
Outlet and the Regulate signal input terminal connect respectively；
The control master chip adjusts the output to the control signal according to the voltage change of the voltage acquisition output terminal
The signal magnitude of input terminal, to control the output of the first of the front end power circuit the power supply output terminal, the second power supply output terminal
Magnitude of voltage；
The control master chip according to the on off state of the LED light string to the level value of the Regulate signal input terminal into
Row synchronous adjustment, including：Join when inputting the constant current to the rear end linear constant current circuit by the reference signal input terminal
When examining voltage so that LED light string is opened, the magnitude of voltage of the Regulate signal input terminal is adjusted so that the switching tube (QB3) is led
It is logical, when inputting the constant current reference voltage so that LED to the rear end linear constant current circuit by the reference signal input terminal
When lamp string turns off, the level value of the adjusting input terminal is adjusted so that the switching tube (QB3) ends.
Preferably, when the control master chip detects the voltage acquisition output terminal and the reference signal input terminal
When voltage difference is more than default threshold value, the control master chip will be exported to the voltage signal of the control signal input and accounted for
Sky is than reducing.
Preferably, the control master chip includes analog-digital converter, for the voltage of the control master chip access to be believed
Number be converted to digital signal.
Preferably, the power supply circuit includes power supply input circuit, switching power circuit, multiple-channel output transformer, LED confessions
Electricity output circuit and main board power supply output circuit；
The power supply signal of access is transmitted to described by the power supply input circuit under the control of the switching power circuit
Multiple-channel output transformer；
The multiple-channel output transformer includes main winding and auxiliary winding；The main winding will pass after the power supply signal transformation
The main board power supply output circuit is transported to, and is exported by the described second power supply output terminal；The auxiliary winding is by the electricity
The LED power supplies output circuit is transmitted to after source signal synchronization transformation, and is exported by the described first power supply output terminal；Institute
The coil ratio for stating main winding and the auxiliary winding is 1：N, N ＞ 0.
Preferably, the feedback adjustment circuit includes opto-coupled feedback unit, voltage stabilizing reference cell, voltage sampling unit and electricity
Press adjustment unit；
The opto-coupled feedback unit includes optocoupler, and the optocoupler is included positioned at the light emitting diode of primary side and positioned at secondary
Optical signal converter, the signal input part of the light emitting diode connect the feedback input end by first resistor (RB131)；
The signal output part of the optical signal converter connects the feedback signal output；
The voltage sampling unit includes the 4th resistance of the series connection being connected between the feedback input end and ground
(RB134) and the 5th resistance (RB135)；
The voltage stabilizing reference cell includes voltage stabilizing standard and is connected to the reference input and cathode of voltage stabilizing standard
Between voltage stabilizing feedback circuit；The reference input of the voltage stabilizing standard is connected to the 4th resistance (RB134) and the 5th resistance
(RB135) locate between connecting, plus earth, cathode connects the signal output part of the light emitting diode；
The voltage-adjusting unit includes the 6th resistance (RB150), and one end of the 6th resistance (RB150) is connected to institute
State and locate between the 4th resistance (RB134) and the series connection of the 5th resistance (RB135), the other end connects the control signal input.
Preferably, the voltage stabilizing feedback circuit includes the first capacitance (CB109) and 3rd resistor (RB133)；
One end of first capacitance (CB109) is connected on the cathode of the voltage stabilizing standard, the other end and the 3rd electricity
Hinder one end series connection of (RB133)；The other end of 3rd resistor (RB133) is connected to the reference input of the voltage stabilizing standard
On.
Preferably, the voltage stabilizing feedback circuit includes the second capacitance (CB110)；
One end of second capacitance (CB110) is connected on the cathode of the voltage stabilizing standard, and the other end is connected to institute
On the reference input for stating voltage stabilizing standard.
Preferably, the voltage stabilizing feedback circuit includes the first capacitance (CB109), 3rd resistor (RB133) and the second capacitance
(CB110)；
One end of first capacitance (CB109) is connected on the cathode of the voltage stabilizing standard, the other end and the 3rd electricity
Hinder one end series connection of (RB133)；The other end of 3rd resistor (RB133) is connected to the reference input of the voltage stabilizing standard
On；
One end of second capacitance (CB110) is connected on the cathode of the voltage stabilizing standard, and the other end is connected to institute
On the reference input for stating voltage stabilizing standard.
Preferably, the output voltage of the magnitude of voltage of the control signal input and the power supply output terminal of the power supply circuit
Correspondence is：When the magnitude of voltage of the control signal input is per 1% duty cycle of stepping, the first power supply output terminal it is defeated
Go out voltage change 0.01V, and the output voltage of the second power supply output terminal changes 0.1V.
Preferably, the voltage signal or PWM that are 0V~3.3V for range of voltage values of the control signal input input
Ripple, the output voltage of the first power supply output terminal, which corresponds to, is adjustable as 11.5V~12.5V, and the second power supply output terminal
Output voltage automatic adaptation.
Present invention also offers a kind of television set, including TV SKD, backlight LED light string, and it is as described above low
The constant current of power consumption and backlight control circuit；
The pressure backlight control circuit is connected respectively with the TV SKD and the backlight LED light string, for beating
When opening the power supply of the television set, according to the operating voltage of the backlight LED light string, automatic adjusument supplies the TV owner
The voltage signal of plate, the backlight LED light string；When closing the power supply of the television set, simultaneously turn off and flow through the backlight LED
The electric current of lamp string.
A kind of constant current of low-power consumption provided by the invention and backlight control circuit and television set, are provided with front end power circuit
With rear end linear constant current circuit, the supply voltage exported using front end power circuit adjusting two-way, and in the power circuit of front end
Feedback adjustment circuit is established, and control signal input is equipped with feedback adjustment circuit, to realize control front end power supply electricity
Road is in the first power supply output terminal and the voltage of the second power supply output terminal；And adapt to go here and there automatically by setting up rear end linear constant current circuit
The change of the LED backlight quantity of connection, the magnitude of voltage after being connected according to LED backlight adjust the control signal input
Magnitude of voltage so that passing through front end power circuit and its feedback adjustment circuit controls the first power supply output terminal, the second power supply
The output voltage of output terminal, and the first power supply output terminal is connected to LED backlight and is powered, and realizes and LED backlight number
The adaptable voltage automation of amount is adjusted, and is reduced the power consumption of circuit switch element, is also passed through voltage detecting circuit and backlight LED light
Series winding connects, and voltage detecting circuit is used to ensure to work as to detect the rear end linear constant current circuit and the LED light string to be powered
During connection conducting, the connection of the voltage acquisition output terminal and the junction is turned on；When detecting the linear Constant Electric Current in the rear end
When road and the connection of the LED light string to be powered disconnect, the connection of the voltage acquisition output terminal and the junction is disconnected.Therefore
LED light string both ends avoid unnecessary power consumption penalty and improve the use longevity of backlight LED equivalent to open circuit, LED without glimmer phenomenon
Life.Present invention also offers the television set that a kind of adaptation power supply is adjusted, constant current as a result of improved low-power consumption and
Backlight control circuit, thus the linear constant current and backlight control circuit are being utilized to TV SKD and backlight of television LED light
When string is powered, above-described beneficial effect is equally reached, improves the service life of backlight LED.
Brief description of the drawings
Fig. 1 is a kind of schematic diagram for linear constant-current modulation circuit that the prior art provides.
Fig. 2 be low-power consumption provided by the invention constant current and backlight control circuit first embodiment structure diagram.
Fig. 3 is a kind of schematic diagram of achievable mode of front end power circuit provided by the invention.
Fig. 4 is a kind of physical circuit schematic diagram of front end power circuit provided by the invention.
Fig. 5 is a kind of circuit diagram of achievable mode of rear end linear constant current circuit provided by the invention.
Fig. 6 is that the circuit diagram of mode can be achieved in the another kind of rear end linear constant current circuit provided by the invention.
Fig. 7 be low-power consumption provided by the invention constant current and backlight control circuit second embodiment structure diagram.
Fig. 8 be low-power consumption provided by the invention constant current and backlight control circuit 3rd embodiment structure diagram.
Fig. 9 is a kind of physical circuit figure of achievable mode of the voltage detecting circuit shown in Fig. 8.
Figure 10 is that the physical circuit figure of mode can be achieved in the another kind of the voltage detecting circuit shown in Fig. 8.
Figure 11 be low-power consumption provided by the invention constant current and backlight control circuit fourth embodiment structure diagram.
Figure 12 be low-power consumption provided by the invention constant current and backlight control circuit the 5th embodiment lamps structure signal
Figure.
Figure 13 is a kind of physical circuit figure of achievable mode of the voltage detecting circuit shown in Figure 12.
Figure 14 is that the physical circuit figure of mode can be achieved in the another kind of the voltage detecting circuit shown in Figure 12.
Figure 15 be low-power consumption provided by the invention constant current and backlight control circuit sixth embodiment structure diagram.
Embodiment
Below in conjunction with the attached drawing in the embodiment of the present invention, the technical solution in the embodiment of the present invention is carried out clear, complete
Site preparation describes.
Embodiment 1
It is that the constant current of low-power consumption provided by the invention and the structure of one embodiment of backlight control circuit are shown referring to Fig. 2
It is intended to.
In the present embodiment, the constant current of the low-power consumption and backlight control circuit include front end power circuit 101, rear end
Linear constant current circuit 103 and voltage detecting circuit 104.
The front end power circuit 101 includes the power supply output terminal of power supply circuit 1011, first OUT1, the second power supply output terminal
OUT2 and feedback adjustment circuit 1012；
Wherein, the feedback adjustment circuit 1012 includes feedback input end A_in, control signal input Cont and feedback
Signal output part B_out；The feedback input end A_in is connected with the described second power supply output terminal OUT2, and the feedback signal is defeated
Outlet B_out is connected with the power supply circuit 1011；The feedback adjustment circuit 1012 is according to the control signal input
The magnitude of voltage of Cont, exports feedback signal, to control the power supply circuit 1011 to described first to the power supply circuit 1011
The magnitude of voltage of power supply output terminal OUT1 and the second power supply output terminal OUT2 are adjusted.
The rear end linear constant current circuit 103 is connected with the cathode LED- of LED light string to be powered, the LED light to be powered
The anode LED+ of string is connected with the described first power supply output terminal OUT1.
The rear end linear constant current circuit 103 is equipped with a connection reference signal input terminal PWM_REF to access constant current reference
Voltage, and according to the size ON/OFF of the constant current reference voltage rear end linear constant current circuit 103 with it is described to be powered
The connection of LED light string.
Linear constant-current circuit 103 passes through voltage detecting circuit with the LED light string junction P to be powered in the rear
104 draw voltage acquisition output terminals A DC all the way, to gather the voltage of the junction, and believes according to the collection result adjustment control
The magnitude of voltage of number input terminal Cont, so as to further adjust the first power supply output terminal OUT1, the second power supply output terminal OUT2
Output voltage.
The voltage detecting circuit 104 is used for：When detect the rear end linear constant current circuit 103 with it is described to be powered
During the connection conducting of LED light string, the connection of the voltage acquisition output terminals A DC and junction P is turned on to gather the junction
Voltage；When the connection for detecting the rear end linear constant current circuit 103 and the LED light string to be powered disconnects, institute is disconnected
State the connection of voltage acquisition output terminals A DC and junction P.
It is a kind of schematic diagram of achievable mode of front end power circuit provided by the invention referring to Fig. 3.
As shown in figure 3, feedback adjustment circuit 1012 can be equipped with optocoupler PCB101, voltage-stablizer UB102 and be connected to described the
Voltage sample electricity that is between two power supply output terminal OUT and ground and being mainly made of the resistance RB134 and resistance RB135 that connect
Road.
Wherein, the optocoupler PCB101 includes light emitting diode (the i.e. foot 1 of optocoupler PCB101 and foot 2 positioned at primary side
Component) and optical signal converter (i.e. the component of the foot 3 of optocoupler PCB101 and foot 4) positioned at secondary.
Voltage-stablizer UB102 by the control signal that the control signal input inputs access to optocoupler PCB101 positioned at original
The light emitting diode on side；Control signal is converted to the position that the optocoupler PCB101 is transferred to after optical signal by the light emitting diode
In the optical signal converter of secondary；The optical signal converter is exported to the feedback signal after converting optical signals to electric signal
Output terminal.
Wherein, the optocoupler PCB101 includes the Light-Emitting Diode positioned at primary side and the optical signal converter positioned at secondary,
Feedback input end A_in and second is used as by resistance R131 positioned at the input terminal (foot 1) of the Light-Emitting Diode of primary side and supplies electricity output
OUT connections are held, and the primary side both ends (foot 1 and foot 2) of optocoupler PCB101 are in parallel with resistance R132；Positioned at the secondary of optocoupler PCB101
The output terminal (foot 4) of optical signal converter be connected to the feedback control of feedback signal output B_out and power supply circuit 1011
Feedback connections in end processed, the other end (foot 3) ground connection of optical signal converter.It should be noted that resistance RB132 is not this reality
Apply the necessary electronic component in the feedback circuit in example.
Voltage-stablizer UB102 preferably uses adjustable precision voltage-stablizer, and the reference voltage of built-in 2.5V (volt), specifically,
It can be realized using the voltage-stablizer of model TL431.Wherein, the anode A ground connection of the adjustable precision shunt voltage-stablizer, it is cloudy
Pole K is connected with the light emitting diode positioned at primary side of the optocoupler PCB101；Reference input R is used to access the control signal
The control signal of input terminal Cont.
As shown in figure 3, the cathode K of voltage-stablizer UB102 is connected with 2 foot of Light-Emitting Diode of optocoupler PCB101 primary sides, voltage stabilizing
The anode A ground connection of device UB102；It is anti-that voltage stabilizing is equipped between the reference input (foot 1) and cathode (foot 3) of voltage stabilizing standard UB102
Current feed circuit；The reference input reference input (foot 1) of the voltage stabilizing standard UB102 is connected to resistance RB134 and resistance
Locate between RB135 series connection, anode (foot 2) ground connection of voltage stabilizing standard UB102, cathode (foot 3) connection of voltage stabilizing standard UB102
The primary side other end (foot 2) of the optocoupler PCB101.
In a kind of achievable mode, the voltage stabilizing feedback circuit includes capacitance CB109 and resistance RB133；The electricity
The one end for holding CB109 is connected on the cathode K of the adjustable precision shunt voltage-stablizer, one end of the other end and resistance RB133
Series connection；The other end of resistance RB133 is connected on the reference input R of the adjustable precision shunt voltage-stablizer.
In another achievable mode, the voltage stabilizing feedback circuit includes capacitance CB110；The capacitance CB110's
One end is connected on the cathode K of the adjustable precision shunt voltage-stablizer, and it is steady that the other end is connected to the adjustable precision shunt
On the reference input R of depressor.
Further, both the above implementation can be combined by the present embodiment, to realize the voltage stabilizing feedback electricity
Road.I.e. described voltage stabilizing feedback circuit is equipped with capacitance CB109, resistance RB133 and capacitance CB110 at the same time.
As shown in figure 3, the cathode K of voltage-stablizer UB102 is connected with 2 foot of light emitting diode of optocoupler PCB101 primary sides, voltage stabilizing
The anode A ground connection of device UB102；One end of resistance RB134 is connected with the reference input R of voltage-stablizer UB102, other end ground connection；
One end of capacitance CB109 is connected on the cathode K of the adjustable precision shunt voltage-stablizer, the other end and the one of resistance RB133
End series connection；The other end of resistance RB133 is connected on the reference input R of the adjustable precision shunt voltage-stablizer；The electricity
The one end for holding CB110 is connected on the cathode K of the adjustable precision shunt voltage-stablizer, and the other end is connected to the adjustable essence
On the reference input R of close shunt regulator.
Further, the reference input R of the adjustable precision shunt voltage-stablizer passes through a divider and the control
Signal input part connects.In this embodiment, it is preferred that the divider is a resistance RB150.
Feedback input end A_in is as shown in figure 3, capacitance CB109 one end is connected with 2 feet of optocoupler PCB101, the other end and electricity
It is connected after resistance RB133 series connection with one end of resistance RB150, the other end of resistance RB150 is as the control signal input
Cont；One end of capacitance CB110 is connected with the cathode K of voltage-stablizer UB102, the reference input R of the other end and voltage-stablizer UB102
Connection；One end of resistance RB135 is connected with feedback input end A_in, and the reference input R of the other end and voltage-stablizer UB102 connects
Connect.Thus, a kind of specific embodiment of feedback circuit 1012 is constituted.
The main improvement of existing feedback adjustment circuit shown in feedback adjustment circuit 1012 and Fig. 1 shown in Fig. 3 is,
Increase by a resistance RB150 on the reference input R of voltage-stablizer UB102, while one is introduced by control signal input Cont
Control signal carries out automated control to the output voltage values of the cathode K of voltage-stablizer UB102, so as to can realize to power supply circuit
1011 and its adjusting of output voltage.
It is a kind of physical circuit schematic diagram of front end power circuit provided by the invention referring to Fig. 4.
The power supply circuit 1011 includes power supply input circuit 11, switching power circuit 12, multiple-channel output transformer
TB101, LED power supply output circuit 13 and main board power supply output circuit 14；
The power supply signal of access is transmitted to by the power supply input circuit 11 under the control of the switching power circuit 12
The multiple-channel output transformer TB101；As shown in figure 4, the multiple-channel output transformer TB101 includes main winding and auxiliary winding.
Wherein, the coil of the foot of 9 feet of multiple-channel output transformer TB101~11 forms primary main winding, multiple-channel output transformer TB101's
The coil of the foot of 1 foot~2 forms secondary main winding；The coil of the foot of 7 feet of multiple-channel output transformer TB101~8 formed it is primary it is secondary around
Group, the coil of the foot of 1 foot of multiple-channel output transformer TB101~6 forms secondary auxiliary winding, and (coil between wherein 1,2 feet is total to
With), and be able to can not also be shared with common sparing winding between secondary major-minor winding.When it is implemented, the main winding is by institute
The main board power supply output circuit 14 is transmitted to after stating power supply signal transformation, and is carried out by the described second power supply output terminal OUT2
Output；The auxiliary winding will be transmitted to the LED power supplies output circuit 13 after the power supply signal synchronization transformation, and by described
First power supply output terminal OUT1 is exported；Therefore, the multiple-channel output transformer TB101 in Fig. 4 has two output voltage, special
Not, in technical field of television sets, the first power supply output terminal OUT1 is preferably the power supply output terminal for supplying LED backlight, the
Two power supply output terminal OUT2 are preferably the power supply output terminal for supplying TV SKD.
In the present embodiment, output voltages of the multiple-channel output transformer TB101 per circle coil be identical, when changing wherein
Output voltage all the way, then the output voltage of another way also will synchronously follow change.For example, the coil of main winding is 2 circles,
Output voltage is 12V, i.e., is 6V per the output voltage of circle coil；Assuming that the output voltage of auxiliary winding is 120V, then auxiliary winding
Coil turn is 20 circles.And the coil turn of main winding and auxiliary winding can be adjusted according to practical application, i.e., described master
The coil ratio of winding and the auxiliary winding is 1：N, N ＞ 0, i.e., when the output voltage of main winding is V1, auxiliary winding it is defeated
It is V2=N*V1 to go out voltage.
It should be noted that the feedback input end A_in of feedback adjustment circuit 1012 can connect the power supply circuit 1011
First power supply output terminal OUT1 or the second power supply output terminal OUT2, has no effect on the implementation of the present embodiment.
The exterior control that the present invention can be accessed by the control signal input Cont of linear regulation feedback adjustment circuit 1012
The size of signal processed, so as to control the magnitude of voltage of the power supply output terminals of the first power supply output terminal OUT1 or second OUT2.Specifically, with
The feedback input end A_in of the feedback adjustment circuit 1012 is connected to the second power supply output terminal of the power supply circuit 1011
Exemplified by OUT2, the basic functional principle of the present embodiment is mainly：
When the output voltage of power supply circuit 1011 raises, (the first power supply output terminal OUT1 and the second power supply output terminal OUT2 are same
When Shi Shenggao), the control signal of control signal input Cont is by resistance RB135 and resistance RB134, resistance RB150 partial pressures
Voltage afterwards is transmitted to the reference input R of voltage-stablizer UB102, and voltage-stablizer UB102 is by the signal value of reference input R and its
Portion's reference voltage is compared.When the signal value of reference input R is more than reference voltage, between voltage-stablizer UB102 anode and cathodes
Voltage reduce, and then optocoupler PCB101A electric current increase, dynamic electric resistive between optocoupler PCB101B collectors and emitter
Small (4 feet of the current collection of optocoupler PCB101 extremely optocoupler, 3 feet of transmitting extremely optocoupler), the voltage between collector and emitter
It is lower；The feedback foot of PWM (Pulse Width Modulation, pulse width modulation) the control chip UB101 connected therewith
The level of COMP is lower, and pwm chip UB101 output duty cycles reduce, so that multiple-channel output transformer TB101's is defeated
Go out voltage reduction.Conversely, when the signal value of reference input R is less than reference voltage, multiple-channel output transformer TB101 may be such that
Output voltage rise.
Therefore, to adjust the size of the voltage signal of the reference input R of voltage-stablizer UB102 accesses so as to controlling transformer
The output voltage of TB101, the present invention is by increasing resistance RB150 and realizing in the side incoming control signal of resistance RB150
This purpose.Specifically, when the output voltage for needing the power supply of modulation second output terminal OUT2, and the inside base of voltage-stablizer UB102
When quasi- voltage is 2.5V, the output voltage values calculation formula of the second power supply output terminal is：Vout2=reference voltage * (1+R135/
R134), wherein, reference voltage is preferably 2.5V.Preferably, a PWM_12V signal can be exported extremely by exterior control chip
The control signal input Cont, via resistance RB150 by PWM_12V signal transmissions to resistance RB134 and resistance RB135 it
Between series connection point (i.e. the reference input R of voltage-stablizer UB102).
When it is implemented, the PWM_12V signals of control signal input Cont can use any one perseverance in 0-3.3V
Constant voltage value, alternatively, PWM (Pulse Width Modulation, pulse width modulation) ripple using certain waveform.According to
The output voltage values calculation formula of two power supply output terminals：Vout2=reference voltages * (1+R135/R134), when PWM_12V signals
Export for 3.3V when, the output voltage of the second power supply output terminal OUT2 is minimum, because the input of control signal input Cont
(1 foot voltage and reference voltage are several when circuit stability works by reference voltage 2.5V of the voltage (3.3v) more than voltage-stablizer UB102
It is equal), so be the equal of that resistance RB150 is connected on the power supply of 3.3V at this time, that is, it is in parallel equivalent to by resistance RB150
On resistance RB135, according to the voltage equation of Vout2, due to resistance RB135 resistance RB150 in parallel, equivalent to electricity
The equivalent resistance for hindering RB135 is reduced, so that output voltage Vout2 is reduced.When PWM_12V signal outputs are 0V, second supplies
The output voltage values of electricity output end OUT2 are maximum, because when PWM_12V signals are 0V, equivalent to control signal input
Cont is grounded, and resistance RB150 is in parallel with resistance RB134, and according to Output Voltage Formula, the equivalent resistance of resistance RB134 diminishes,
The voltage of the reference input R of voltage-stablizer UB102 diminishes, therefore the output voltage rise of the second power supply output terminal OUT2.
As it can be seen that the control signal inputted by the control signal input Cont of linear regulation feedback adjustment circuit 1012
(voltage signal or PWM ripples of 0V~3.3V as escribed above), may be such that the output voltage of the second power supply output terminal OUT2 in reality
(Vout2_max=12.5V, Vout2_min=11.5V) is adjusted between the common voltage scope 11.5V~12.5V of border, from
And realize fine setting；Similarly, under the action of multiple-channel output transformer TB101, the output voltage of the first power supply output terminal OUT1
It will realize that synchronous automatic adaptation is adjusted.
In concrete application occasion, under product ideal case (power supply circuit output reduce), can be by linear regulation outside
Control signal input Cont from portion's control chip to feedback adjustment circuit 1012 input control signal for high level (such as
3.3V), it is minimum output voltage so as to make the voltage of the second of power supply circuit 1011 the power supply output terminal OUT2 outputs, can subtracts
The stand-by power consumption of few TV SKD.
In addition, the LED light string to be powered is in series by multiple LED light, with the quantity of LED light string to be powered
Increase, required supply voltage constantly increases after multiple LED series connection, it is therefore desirable to the output of the first power supply output terminal OUT1
Voltage can adaptively respond the number change of LED, automatically adjust its output voltage values.
It is the circuit theory of two kinds of achievable modes of rear end linear constant current circuit provided by the invention referring to Fig. 5~6
Figure.
When it is implemented, in the rear in linear constant-current circuit 103, the relatively adjustment circuit 1031 is put including computing
The reverse input end of big device UB1A, the operational amplifier UB1A pass through a resistance RB12 and the reference signal input terminal PWM_
REF connections；The positive input of the operational amplifier UB1A is connected with current feedback circuit, the operational amplifier UB1A's
The control terminal that output terminal passes through a control circuit module connecting valve pipe QB1.Specifically, as shown in Figure 5,6, current feedback electricity
Road includes the constant current detection resistance composed in parallel by resistance RB6, resistance RB7, resistance RB8 and resistance RB9, further includes resistance RB5
With capacitance CB5.Wherein, it is connected by resistance RB6, resistance RB7, resistance RB8 with one end of the resistance RB9 constant current detection resistances formed
On one end of resistance RB5, other end ground connection；The positive that the other end of resistance RB5 is connected to the operational amplifier UB1A is defeated
Enter on end.One end ground connection of the capacitance CB5, the other end are connected on the normal phase input end of the operational amplifier UB1A.Its
The circuit of middle resistance RB5 and capacitance CB5 composition can carry out the signal for the positive input for being input to operational amplifier UB1A
Filtering.
Preferably, the positive input of the operational amplifier UB1A is also associated with a clamp diode DB1, to protect
State the normal work for comparing adjustment circuit 1031.
In the rear in linear constant-current circuit 103, the constant-current control circuit 1032 further include control circuit module and
Switching tube QB1.Switching tube QB1 can be triode or MOS (Metal-Oxid-Semiconductor, metal oxide half
Conductor) field-effect transistor, abbreviation metal-oxide-semiconductor or field-effect transistor.Wherein, conducting, cut-off or the conducting degree of switching tube QB1
State is associated with the physical characteristic of its own.For example, when switching tube QB1 is triode, according to the C-V characteristic of triode
Curve, there is saturation region, amplification region and cut-off region, and the voltage signal between the emitter and collector of triode is produced respectively
Raw different influence, such as when triode operation is in saturation region, (leads between the emitter and collector of triode equivalent to short circuit
Logical state).
The rear end linear constant current circuit 103 is by reference to signal input part PWM_REF, to access constant current reference voltage
VREF, and according to the constant current reference voltage VREFSize control the conducting, cut-off or conducting degree of the switching tube QB1, from
And the connection of rear end linear constant current circuit 103 described in ON/OFF and the LED light string to be powered
In the present embodiment, as shown in figure 5, when the switching tube QB1 is triode, the constant-current control circuit 1032
It is connected by the collector of the triode with one end (LED-) of the LED light string to be powered；The emitter of the triode
It is connected with the anode of the clamp diode DB1, the base stage of the triode passes through the control circuit module and the computing
The output terminal connection of amplifier UB1A；As shown in fig. 6, when the switching tube QB1 is field-effect transistor, the current constant control
Circuit 1032 is connected by the drain electrode of the field-effect transistor with one end (LED-) of the LED light string to be powered；The field
The source electrode of effect transistor is connected with the anode of the clamp diode DB1, and the grid of the field-effect transistor passes through described
Control circuit module and the output terminal of the operational amplifier UB1A.
When it is implemented, the minus earth of clamp diode DB1, anode is connected to operational amplifier by resistance RB5
The positive input of UB1A.After the startup of rear end linear constant current circuit 103, by the adjustment of operational amplifier UB1A, it is positive
Input terminal connects the magnitude of voltage and its constant current reference voltage V that reversely input accesses that constant current detection resistance is gotREFIt is equal,
Then as constant current reference voltage VREFDuring turn-on voltage (about 0.7V) higher than clamp diode DB1, clamp diode DB1 will
Conducting ground connection, i.e., by the voltage at resistance RB6, resistance RB7, resistance RB8 and resistance RB9 the constant current detection resistance both ends composed in parallel
Value is clamped diode DB1 and is limited, and therefore, clamp diode DB1 plays certain protective effect.
Also, due to the emitter (switching tube QB1 is triode) or source electrode of switching tube QB1 (switching tube QB1 is metal-oxide-semiconductor)
It is connected with the anode of clamp diode DB1, therefore the constant current value for the switching tube QB1 that circulates can be calculated by the following formula：
As constant current reference voltage VREFDuring turn-on voltage higher than clamp diode DB1, the constant current of circulation switching tube QB1
Signal is IConstant currentThe resistance value of the turn-on voltage of=DB1/constant current detection resistance；As constant current reference voltage VREFLess than clamp diode
During the turn-on voltage of DB1, the constant current signal of circulation switching tube QB1 is IConstant current=constant current reference voltage VREF/ constant current detection resistance
Resistance value.In general, the turn-on voltage of clamp diode DB1 is 0.7V, the resistance value of constant current detection resistance is resistance RB6, resistance
Equivalent resistance after RB7, resistance RB8 and resistance RB9 parallel connections.
In the present embodiment, the first power supply output terminal is connected to the cathode LED+ of LED light string, passes through the perseverance of switching tube QB1
Flow control, then constant current detection resistance (resistance RB6, resistance RB7, the parallel resistance of resistance RB8 and resistance RB9) is concatenated to ground, it is permanent
The size of current of LED light string is converted into voltage signal and is linked into operational amplifier UB1A and constant current reference voltage by stream detection resistance
VREF(it is controlled by exterior master chip, or access fixed voltage, the constant current value I then exported if fixed voltageConstant currentIt is then solid
Definite value, it is impossible to carry out the adjusting of constant current size) it is compared and amplifies, so that the electric current of controlling switch pipe QB1 adjustment LED light strings
Keep constant.
The plurality of LEDs lamp when it is implemented, LED light string can generally connect, wherein the operating voltage of single LED is generally 2.8V
~3.4V, the operating voltage after plurality of LEDs lamp string joins will accordingly increase.By taking switching tube QB1 is metal-oxide-semiconductor as an example, switching tube QB1's
Voltage V between drain electrode and source electrodeDS=VOUT1- LED light string operating voltage-constant current reference voltage VREF.Therefore, rear end is linear
After constant-current circuit 103 enters working status, the voltage V between the drain electrode of switching tube QB1 and source electrodeDSIt will be subject to LED light string
The influence of operating voltage size, may also be subjected to the crossmodulation (general range 7%) of multiple-channel output transformer TB101 in addition
Influence.
In the prior art, with the change of LED light string voltage, the drain-source voltage V of switching tube QB1DSVoltage is also synchronously sent out
Changing, this Partial Power (V of switching tube QB1DS* constant current value IConstant current) form that will be converted into heat comes out, VDSElectricity
Pressure is bigger, and the power consumption of switching tube QB1 is bigger, and temperature is higher.Therefore the excessive switching tube QB1 of power consumption can reduce power-efficient and
Switching tube QB1 is caused to overheat and be easily damaged.In order to reduce the temperature of switching tube QB1, multiple metal-oxide-semiconductors or triode can be used
Parallel connection is used as switching tube QB1, but this technical solution result in the increase of cost.And in the present embodiment, it can solve
The power problems of above-described switching tube QB1.Specifically, the present embodiment by the constant-current control circuit 1032 with it is described
LED light string junction P to be powered draws voltage acquisition output terminals A DC all the way, to detect the change of the voltage of LED light string to be powered in real time
Change, the pressure drop between voltage acquisition output terminals A DC and reference signal input terminal PWM_REF sets a threshold value, alternatively, being electricity
The output voltage of pressure collection output terminals A DC sets a steady state value (voltage V of reference signal input terminal PWM_REFREFGenerally compared with
It is small), when the pressure drop between voltage acquisition output terminals A DC and reference signal input terminal PWM_REF is more than the threshold value, or voltage
It is defeated by adjusting the control signal in front end power circuit 101 when the output voltage of collection output terminals A DC is more than the steady state value
Enter to hold the control signal PWM_12V of Cont, control optocoupler PCB101 by the situation of change (i.e. first of the operating voltage of LED light string
The voltage change situation of power supply output terminal OUT1) feed back to pwm chip UB101, pwm chip UB101 controlling switches
Pipe QB101 changes duty cycle, so that the magnitude of voltage of voltage acquisition output terminals A DC subtracts reference signal input terminal PWM_REF
Magnitude of voltage equal or close to the default threshold value, (or the magnitude of voltage of voltage acquisition output terminals A DC is equal or close to described
Steady state value), therefore, the present embodiment can pass through the control signal PWM_12V of control signal input Cont, stop voltage collection
Pressure drop between output terminals A DC and reference signal input terminal PWM_REF, so as to reduce the drain-source voltage V of switching tube QB1DSIt is subject to
The influence of the voltage change of LED light string, reduces the power consumption of switching tube QB1 and ensure that power-efficient.Also, end line in the rear
Property constant-current circuit is also connected voltage acquisition output terminal to gather with the LED light string junction to be powered by voltage detecting circuit
The voltage of the junction, the voltage detecting circuit are used for：When detect the rear end linear constant current circuit with it is described to be powered
During the connection conducting of LED light string, the connection of the voltage acquisition output terminal and the junction is turned on；When detecting the back end of line
Property constant-current circuit and the LED light string to be powered connection when disconnecting, disconnect the voltage acquisition output terminal and the junction
Connection.So that LED light string both ends avoid unnecessary power consumption penalty and improve backlight equivalent to open circuit, LED without glimmer phenomenon
The service life of LED.
Embodiment 2
It is that the constant current of low-power consumption provided by the invention and the structure of second embodiment of backlight control circuit are shown with reference to figure 7
It is intended to.
The present embodiment is on the basis of embodiment 1, further, the constant current and backlight control of low-power consumption provided in this embodiment
Circuit processed further includes a control master chip 105.Wherein, front end power circuit 101 and rear end linear constant current circuit 103 and voltage inspection
The essential structure of slowdown monitoring circuit 104 is identical with previously described embodiment with operation principle, and details are not described herein.
Control master chip 105 and the control signal input Cont, the reference signal input terminal PWM_REF with
And the voltage acquisition output terminals A DC is connected respectively；
The control master chip 105 adjusts the output to the control according to the voltage change of the voltage acquisition output terminals A DC
The signal magnitude of signal input part Cont processed, to control the first of the front end power circuit 101 the power supply output terminal OUT1, second
The output voltage values of power supply output terminal OUT2；And by the reference signal input terminal PWM_REF to the rear end linear constant current
Circuit 103 inputs the constant current reference voltage VREF。
Specifically, when the control master chip 105 detects that the voltage acquisition output terminals A DC and the reference signal are defeated
When entering to hold the voltage difference of PWM_REF to be more than default threshold value, the control master chip 105 will export defeated to the control signal
Enter to hold the voltage signal duty cycle of Cont to reduce.When it is implemented, the control master chip 105 is built-in with analog-digital converter, use
Digital signal is converted in the voltage signal for accessing the control master chip 105.Obtained from voltage acquisition output terminals A DC collections
Voltage signal first pass around the conversion of analog-digital converter after, obtain corresponding digital signal, then by controlling in master chip 105
Other processing units processing.Since excessive input voltage value can influence the normal work of analog-digital converter, and closing
The magnitude of voltage of P points easily causes the resistance between former connection analog-digital converter of the prior art to produce faint electricity during LED light string
Signal is flowed, so that LED backlight produces glimmer phenomenon.Since the present embodiment is provided with voltage detecting circuit 104, Ke Yi
When turning off backlight electric power, the current signal for effectively separating voltage detecting circuit 104 is moved back in LED light string, avoids " glimmer
The generation of phenomenon ".
The present embodiment is defeated to control signal input Cont, the reference signal as a result of same control master chip
Enter to hold the signal of tri- terminals of PWM_REF and the voltage acquisition output terminals A DC to be handled, therefore have previously described
, further can be in real time according to reference signal input terminal PWM_REF and voltage acquisition output terminals A DC on the basis of imitating effect
Signal intensity, and send corresponding control signal to control signal input Cont, therefore can reach rapidly to LED light string
The beneficial effect that the change of operating voltage is responded.
Embodiment 3
It is that the constant current of low-power consumption provided by the invention and the structure of 3rd embodiment of backlight control circuit are shown with reference to figure 8
It is intended to.
In the same manner as in Example 1, the constant current of the low-power consumption of the present embodiment and backlight control circuit include front end power circuit
101st, rear end linear constant current circuit 103 and voltage detecting circuit 104.Wherein, shown front end power circuit 101 and rear end are linearly permanent
Current circuit 103 is consistent with the structure and operation principle of embodiment 1, omits description herein.As different from Example 1, this implementation
Cathode of the voltage detecting circuit 104 of example including diode DB2 and pull-up resistor RB18, the diode DB2 is connected to described
The cathode LED- of LED light string, the anode of diode DB2 are connected to one end of pull-up resistor RB18, and pull-up resistor RB18's is another
Terminate into high level；The anode of the diode DB2 connects the voltage acquisition output terminals A DC.When it is implemented, and resistance
The high level VCC of RB18 connections can be carried by the constant-current control circuit 1032 that the control terminal identical with switching tube QB1 controls
For.
As shown in figure 8, output terminal all the way is drawn in the junction P of constant-current control circuit 1032 and LED light string cathode, with two
Pole pipe DB2 cathodes connect, and when the LED light string is opened, diode DB2 conductings, the voltage detecting circuit 104 passes through two poles
Pipe DB2 detects the operating voltage of the LED light string, so that controlling the feedback circuit 1012 to adjust described first supplies electricity output
Hold OUT1, the output voltage of the second power supply output terminal OUT2；When the LED light string is closed, diode DB2 reversely ends, and closes
Stop the electric current through the LED light string.
Specifically, the constant current of low-power consumption provided in this embodiment and the main operational principle of backlight control circuit are：Beating
When opening backlight of television power supply, switching tube QB1 conductings enter working status, the voltage for the P points being connected with LED light string is limited
It is (logical in collector (when switching tube QB1 is triode) or the magnitude of voltage to drain (when switching tube QB1 is field-effect transistor)
Often less than 3.3V) on, meanwhile, the access of high level VCC is so that the diode DB2 and voltage VA of the tie point of resistance RB18 is higher than
The voltage of P points, therefore, diode DB2 conductings, circuit carry out work by resistance RB18, diode DB2 and switching tube QB1 circuits
Make.At this time, the voltage VA=VDB2+VQB1 of the tie point of diode DB2 and resistance RB18；In closing television machine backlight electric power
When, rear end linear constant current circuit 103 disconnects switching tube QB1 with LED light string and enters cut-off state, and LED light string both ends are subject to constant pressure
The influence of circuit and there is the high level much larger than 3.3V at LED- ends, therefore diode DB2 reversely ends, LED light string and electricity
Open circuit is equivalent between pressure detection circuit 104, i.e., LED light string will be without weak current by that thus will not produce glimmer phenomenon.
Fig. 9 is a kind of physical circuit figure of achievable mode of voltage detecting circuit provided in this embodiment.
The voltage detecting circuit 104 includes the cathode connection of diode DB2 and pull-up resistor RB18, the diode DB2
In the cathode LED- of the LED light string, the anode of diode DB2 is connected to one end of pull-up resistor RB18, pull-up resistor RB18
Other end access high level (be preferably 3.3V)；When it is implemented, high level VCC can be by the control identical with switching tube QB1
The constant-current control circuit 1032 of end control processed provides.
The anode of the diode DB2 connects the voltage acquisition output terminals A DC.The anode of the diode DB2 is also logical
Cross the resistance RB16 connections voltage acquisition output terminals A DC.At this time, the output voltage of voltage acquisition output terminals A DC is：VADC=
VA*RB17/(RB16+RB17).When the LED light string is opened, diode DB2 conductings, the voltage detecting circuit 104 passes through
Diode DB2 detects the operating voltage of the LED light string, so as to control the feedback adjustment circuit 1012 to adjust described first
The output voltage of power supply output terminal OUT1, the second power supply output terminal OUT2；When the LED light string is closed, diode DB2 is reverse
Cut-off, shut-off flow through the electric current of the LED light string.
Output terminals A DC and diode DB2 all the way is drawn in the junction P of constant-current control circuit 1032 and LED light string cathode
Cathode connects, and when the LED light string is opened, diode DB2 is turned on, and the work of the LED light string is detected by diode DB2
Resistance RB16 is flowed through as voltage and is transmitted to external control devices or chip, so as to be adjusted by controlling the feedback circuit described
The output voltage of first power supply output terminal OUT1, the second power supply output terminal OUT2；When the LED light string is closed, i.e. switching tube
When QB1 ends, diode DB2 reversely ends, and shut-off flows through the electric current of the LED light string.
Specifically, the main operational principle of the backlight control circuit of low-power consumption provided in this embodiment is：
When opening backlight of television power supply, switching tube QB1 conductings enter working status, the P points that will be connected with LED light string
Voltage be limited in collector (when switching tube QB1 is triode) or drain electrode (when switching tube QB1 is field-effect transistor)
Magnitude of voltage (typically smaller than 3.3V) on, meanwhile, the access of high level VCC is so that the tie point of diode DB2 and resistance RB18
Voltage VAHigher than the voltage of P points, therefore, diode DB2 conductings, circuit passes through resistance RB18, diode DB2 and switching tube
QB1 circuits work.At this time, the voltage V of the tie point of diode DB2 and resistance RB18A=VDB2+VQB1；At this time, voltage is examined
The output voltage for surveying output terminals A DC is：VADC=VA*RB17/(RB16+RB17).In closing television machine backlight electric power, switch
Pipe QB1 enters cut-off state, and LED light string both ends keep constant pressure and there are the high level much larger than 3.3V, therefore two at LED- ends
Pole pipe DB2 reversely ends, and open circuit is equivalent between LED light string and voltage detecting circuit 104, i.e. LED light string will be without weak current
By because without producing glimmer phenomenon.
Preferably, the voltage detecting circuit 104 provided in this embodiment further includes a filter circuit of pressure-stabilizing 1042；It is described
Filter circuit of pressure-stabilizing 1042 is connected between the voltage acquisition output terminals A DC and ground.
The filter circuit of pressure-stabilizing 1042 includes zener diode D1, capacitance CB7 and resistance RB17；And zener diode D1
Cathode, one end of capacitance CB7 and one end of resistance RB17 be commonly connected on the voltage acquisition output terminals A DC；Voltage stabilizing two
The other end of the anode of pole pipe D1, the other end of capacitance CB7 and resistance RB17 is grounded jointly.Wherein, the master of zener diode D1
Act on be prevent voltage detecting circuit 104 operation irregularity or when switching tube QB1 is turned off because high level VCC voltages are more than
3.3V and cause the output voltage of port ADC excessive so that burn the device that voltage acquisition output terminals A DC is connected situation hair
It is raw.
Figure 10 is that the physical circuit figure of mode can be achieved in the another kind of voltage detecting circuit provided in this embodiment.
The voltage detecting circuit 104 includes the cathode connection of diode DB2 and pull-up resistor RB18, the diode DB2
In the cathode LED- of the LED light string, the anode of diode DB2 is connected to one end of pull-up resistor RB18, pull-up resistor RB18
Other end access high level (be preferably 3.3V)；The anode of the diode DB2 also passes through the diode DB3 connections voltage
Gather output terminals A DC.The anode of the diode DB3 is connected with the anode of diode DB2；The cathode of the diode DB3 is made
For the voltage acquisition output terminals A DC, at this time, the output voltage of voltage acquisition output terminals A DC is：VADC=VA-VDB3。
The output voltage V of voltage acquisition output terminals A DCADCIt will be transmitted to external control devices and carry out processing analysis, with basis
Analysis result controls the working status of front end power circuit 101, so that it is defeated to control the first power supply output terminal OUT1 and second to power
The output voltage of outlet OUT2.
Preferably, the voltage detecting circuit 104 provided in this embodiment further includes a filter circuit of pressure-stabilizing 1042；It is described
Filter circuit of pressure-stabilizing 1042 is connected between the voltage acquisition output terminals A DC and ground.
The filter circuit of pressure-stabilizing 1042 includes zener diode D1, capacitance CB7 and resistance RB17；And zener diode D1
Cathode, one end of capacitance CB7 and one end of resistance RB17 be commonly connected on the voltage acquisition output terminals A DC；Voltage stabilizing two
The other end of the anode of pole pipe D1, the other end of capacitance CB7 and resistance RB17 is grounded jointly.Wherein, the master of zener diode D1
Act on be prevent voltage detecting circuit 104 operation irregularity or when switching tube QB1 is turned off because high level VCC voltages are more than
3.3V and cause the output voltage of port ADC excessive so that burn the device that voltage acquisition output terminals A DC is connected situation hair
It is raw.
In the present embodiment, the main operational principle of the voltage stabilizing backlight control circuit of low-power consumption provided in this embodiment with
The basic functional principle of Fig. 9 illustrated embodiments is identical, mainly includes：When opening backlight of television power supply, switching tube QB1 is led
Logical to enter working status, the access of high level VCC causes diode DB2DB2 to turn on, and circuit passes through resistance RB18, diode DB2
Work with switching tube QB1 circuits, the voltage V of the tie point of diode DB2 and resistance RB18A=VDB2+VQB1, wherein, VDB2
Represent the pressure drop formed when electric current flows through diode DB2 at the input of diode DB2, output both ends, VQB1Represent that electric current flows through out
Close pipe QB1 when switching tube QB1 input, output both ends formed pressure drop.Meanwhile diode DB3 is turned on, by voltage VATransmission
To voltage detecting output terminals A DC, at this time, the output voltage of voltage detecting output terminals A DC is：VADC=VA-VDB3.In closing television
During machine backlight electric power, switching tube QB1 enters cut-off state, LED light string both ends keep constant pressure thus exist at LED- ends and be much larger than
The high level of 3.3V, therefore diode DB2 reversely ends, and open circuit is equivalent between LED light string and voltage detecting circuit 104, i.e.,
LED light string will be without weak current by because without producing glimmer phenomenon.
Embodiment 4
It is that the constant current of low-power consumption provided by the invention and the structure of fourth embodiment of backlight control circuit are shown with reference to figure 11
It is intended to.
The present embodiment is on the basis of embodiment 3, further, the constant current and backlight control of low-power consumption provided in this embodiment
Circuit processed further includes a control master chip 105.Wherein, front end power circuit 101 and rear end linear constant current circuit 103 and voltage inspection
The essential structure of slowdown monitoring circuit 104 is identical with previously described embodiment with operation principle, and details are not described herein.
Control master chip 105 and the control signal input Cont, the reference signal input terminal PWM_REF with
And the voltage acquisition output terminals A DC is connected respectively；
The control master chip 105 adjusts the output to the control according to the voltage change of the voltage acquisition output terminals A DC
The signal magnitude of signal input part Cont processed, to control the first of the front end power circuit 101 the power supply output terminal OUT1, second
The output voltage values of power supply output terminal OUT2；And by the reference signal input terminal PWM_REF to the rear end linear constant current
Circuit 103 inputs the constant current reference voltage VREF。
Specifically, when the control master chip 105 detects that the voltage acquisition output terminals A DC and the reference signal are defeated
When entering to hold the voltage difference of PWM_REF to be more than default threshold value, the control master chip 105 will export defeated to the control signal
Enter to hold the voltage signal duty cycle of Cont to reduce.When it is implemented, the control master chip 105 is built-in with analog-digital converter, use
Digital signal is converted in the voltage signal for accessing the control master chip 105.Obtained from voltage acquisition output terminals A DC collections
Voltage signal first pass around the conversion of analog-digital converter after, obtain corresponding digital signal, then by controlling in master chip 105
Other processing units processing.Since excessive input voltage value can influence the normal work of analog-digital converter, and closing
The magnitude of voltage of P points easily causes the resistance between former connection analog-digital converter of the prior art to produce faint electricity during LED light string
Signal is flowed, so that LED backlight produces glimmer phenomenon.Since the present embodiment is provided with voltage detecting circuit 104, Ke Yi
When turning off backlight electric power, by controlling diode DB2 to be moved back to so as to effectively separate the current signal of voltage detecting circuit 104
In LED light string, the generation of " glimmer phenomenon " is avoided.
The present embodiment is defeated to control signal input Cont, the reference signal as a result of same control master chip
Enter to hold the signal of tri- terminals of PWM_REF and the voltage acquisition output terminals A DC to be handled, therefore have previously described
, further can be in real time according to reference signal input terminal PWM_REF and voltage acquisition output terminals A DC on the basis of imitating effect
Signal intensity, and send corresponding control signal to control signal input Cont, therefore can reach rapidly to LED light string
The beneficial effect that the change of operating voltage is responded.
In 3~example of above-described embodiment 4, the first embodiment and second of embodiment of voltage detecting circuit 104
It is avoided that when closing backlight LED light string power supply, avoids voltage acquisition output terminals A DC or voltage detecting output terminals A DC from playing a reversed role
Current signal flow into backlight LED so that backlight LED produce glimmer phenomenon.But as shown in Figure 9 and Figure 10, due to electricity
The first embodiment and second of embodiment for pressing detection circuit 104 introduce high level VCC, therefore, even in pass
Close in the state of backlight, resistance RB18 still can produce voltage VA and export to voltage detecting output terminals A DC, because regardless of whether LED light
Whether string closes, and voltage detecting output terminals A DC is there are certain voltage signal, so that its exterior control connected is set
Standby (such as analog-digital converter) is chronically at working status, thus adds the unnecessary work(of external control devices to a certain extent
Consumption.Therefore, it is necessary to work out the other embodiment on voltage detecting circuit 104.
Embodiment 5
With reference to figure 12, be low-power consumption provided by the invention constant current and backlight control circuit the 5th embodiment lamps structure
Schematic diagram.
As embodiment 1 or 3, the constant current of the low-power consumption of the present embodiment and backlight control circuit include front end power circuit
101st, rear end linear constant current circuit 103 and voltage detecting circuit 104.Wherein, shown front end power circuit 101 and rear end are linearly permanent
Current circuit 103 is consistent with the structure and operation principle of embodiment 1, omits description herein.
Unlike embodiment 1 or 3, the voltage detecting circuit 104 of the present embodiment includes switching tube QB3, the switch
The input terminal of pipe QB3 is connected to the cathode LED- (i.e. junction P) of the LED light string, the output terminal connection of the switching tube QB3
The control terminal of the voltage acquisition output terminals A DC, the switching tube QB3 connect a Regulate signal input terminal Cont_S, pass through tune
The magnitude of voltage of the Regulate signal input terminal Cont_S is saved, makes the rear end linear constant current circuit and the LED light string to be powered
Connection conducting while switching tube QB3 conducting, the connection of the rear end linear constant current circuit and the LED light string to be powered breaks
Switching tube QB3 ends while opening.
As shown in figure 12, output terminal all the way is drawn in the junction P of constant-current control circuit 1032 and LED light string cathode, with
The input terminal of switching tube QB3 connects, and the big of the constant current reference voltage is adjusted when passing through the reference signal input terminal PWM_REF
It is small and while open the LED light string, adjusted by adjusting the magnitude of voltage of the Regulate signal input terminal so that described open
Close pipe QB3 conductings；It is electric when inputting the constant current reference to the rear end linear constant current circuit by the reference signal input terminal
When pressing so that LED light string turns off, the level value of the adjusting input terminal is adjusted so that the switching tube QB3 ends, so as to close
Stop the electric current through the LED light string.The voltage detecting circuit 104 detects institute by the voltage acquisition output terminals A DC
The operating voltage of LED light string is stated, so as to control the feedback adjustment circuit 1012 to adjust the first power supply output terminal OUT1, the
The output voltage of two power supply output terminal OUT2.
Figure 13 is a kind of physical circuit figure of achievable mode of voltage detecting circuit provided in this embodiment.
Specifically, the voltage detecting circuit 104 includes voltage acquisition input terminal (being connected with P points), Regulate signal inputs
Hold Cont_S and voltage acquisition output terminals A DC；An output terminal is drawn in the junction of switching tube (QB1) and the LED light string, with
The voltage acquisition input terminal connection.
As shown in figure 13, voltage detecting circuit 104 includes switching tube QB3, resistance RB19 and resistance RB20；Wherein, switch
Pipe QB3 can be the triode of NPN type or the metal-oxide-semiconductor of N-channel.By taking switching tube QB3 is the triode of NPN type as an example, switching tube
The collector of QB3 is connected on switching tube QB1 and the junction P of LED light string, and the transmitter of switching tube QB3 is with resistance RB19's
One end connects, and the other end of resistance RB19 is connected with the voltage acquisition output terminals A DC；One end of resistance RB20 and switching tube
The base stage connection of QB3, the other end of resistance RB20 is as Regulate signal input terminal Cont_S.By controlling the Regulate signal defeated
Enter to hold the level value of Cont_S, when the LED light string turns on, controlling switch pipe QB3 is conducting state, by switching tube QB1 with
The magnitude of voltage V of the junction P of the LED light stringACollection is exported to the voltage acquisition output terminals A DC；Closed in the LED light string
When disconnected, controlling switch pipe QB3 is cut-off state, is connected so as to disconnect the voltage detecting circuit 104 with the electric of the junction P
Connect.
Preferably, the switch controlling signal of switching tube QB1 is synchronous with the Regulate signal of Regulate signal input terminal Cont_S, and
Preferably it is controlled using same control terminal.
Specifically, in backlight open, controlling switch pipe QB1 is in the conduction state, while is Regulate signal input terminal
Cont_S accesses high level, then switching tube QB3 is synchronously turned on, then the electric current for flowing through LED light string is the setting electric current of circuit, and electric
The magnitude of voltage of pressure collection output terminals A DC is：VADC=VA* RB17/ (RB19+RB17), VADCSignal sends external control terminal to.
When closing backlight, when controlling switch pipe QB1 is turned off, and low level is set for Regulate signal input terminal Cont_S,
Then switching tube QB3 synchronously ends, and equivalent to open circuit between LED light string and voltage detecting circuit 104, therefore LED light string is complete
Close, no glimmer phenomenon, also, since switching tube QB3 is in cut-off state, voltage acquisition output terminals A DC does not have in theory
There is voltage signal, therefore, its external control terminal connected is without carrying out at correlation the signal of voltage acquisition output terminals A DC
Reason.For example, when external control terminal includes analog-digital converter, then will not be to voltage acquisition output terminals A DC when backlight is closed
Signal carry out analog-to-digital conversion (because voltage acquisition output terminals A DC no signals export).
Figure 14 is that the physical circuit figure of mode can be achieved in the another kind of voltage detecting circuit provided by the invention.
In the embodiment of voltage detecting circuit 104, it is on the basis of the embodiment that Figure 13 is provided, further
Ground, is additionally provided with switching tube QB4, resistance RB22 and resistance RB23.Wherein, switching tube QB4 can be triode or metal-oxide-semiconductor.
Specifically, by taking switching tube QB4 is triode as an example, on the basis of the embodiment that Figure 13 is provided, resistance RB20
One end be connected with the base stage of switching tube QB3, the other end of resistance RB20 is connected with the collector of switching tube QB4, switching tube QB4
Emitter ground connection；The base stage of switching tube QB4 after series resistor RB22 by being grounded, and by being used as tune after series resistor RB23
Signal input part Cont_S is saved, i.e., one end of resistance RB23 is as Regulate signal input terminal Cont_S, the other end and switching tube QB4
Base stage connection, the Regulate signal access switching tube QB4 that Regulate signal input terminal Cont_S is accessed.
Preferably, the switch controlling signal of switching tube QB1 is synchronous with the Regulate signal of Regulate signal input terminal Cont_S, and
Preferably it is controlled using same control terminal.Therefore, the basic functional principle of the voltage regulator circuit 104 of present embodiment
It is：
In backlight open, controlling switch pipe QB1 is in the conduction state, while is accessed for Regulate signal input terminal Cont_S
High level, then switching tube QB4 synchronously conductings, then the electric current for flowing through LED light string is the setting electric current of circuit, and switching tube QB4 is turned on
So that switching tube QB3 is turned on after resistance RB21 carries out partial pressure with resistance RB20 afterwards, the magnitude of voltage of voltage acquisition output terminals A DC is：
VADC=VA* RB17/ (RB19+RB17), VADCSignal sends external control terminal to.
When closing backlight, when controlling switch pipe QB1 is turned off, and low level is set for Regulate signal input terminal Cont_S,
Then switching tube QB4, switching tube QB3 synchronously end, equivalent to open circuit between LED light string and voltage detecting circuit 104, therefore LED
Lamp string is fully closed, no glimmer phenomenon, also, since switching tube QB3 is in cut-off state, voltage acquisition output terminal
ADC does not have voltage signal in theory, and therefore, its external control terminal connected is without the letter to voltage acquisition output terminals A DC
Number carry out relevant treatment.For example, when external control terminal includes analog-digital converter, then voltage will not be adopted when backlight is closed
The signal for collecting output terminals A DC carries out analog-to-digital conversion (because voltage acquisition output terminals A DC no signals export).
Preferably, a filter circuit of pressure-stabilizing 1041 is equipped with the voltage detecting circuit 104 shown in Figure 13 or Figure 14；Institute
Filter circuit of pressure-stabilizing 1041 is stated to be connected between the voltage acquisition output terminals A DC and ground.
The filter circuit of pressure-stabilizing 1041 includes zener diode D1, capacitance CB7 and resistance RB17；And zener diode D1
Cathode, one end of capacitance CB7 and one end of resistance RB17 be commonly connected on the voltage acquisition output terminals A DC；Voltage stabilizing two
The other end of the anode of pole pipe D1, the other end of capacitance CB7 and resistance RB17 is grounded jointly.Wherein, the master of zener diode D1
Act on be prevent voltage detecting circuit 104 operation irregularity or when switching tube QB1 is turned off because high level VCC voltages are more than
3.3V and cause the output voltage of port ADC excessive so that burn the device that voltage acquisition output terminals A DC is connected situation hair
It is raw.
Embodiment 6
It is that the constant current of low-power consumption provided by the invention and the structure of sixth embodiment of backlight control circuit are shown referring to Figure 15
It is intended to.
The present embodiment is on the basis of embodiment 5, further, the constant current and backlight control of low-power consumption provided in this embodiment
Circuit processed further includes a control master chip 105.Wherein, front end power circuit 101 and rear end linear constant current circuit 103 and voltage inspection
The essential structure of slowdown monitoring circuit 104 is identical with previously described embodiment with operation principle, and details are not described herein.
Control master chip 105 and the control signal input Cont, the reference signal input terminal PWM_REF,
Voltage acquisition output terminals A DC and Regulate signal the input terminal Cont_S is connected respectively；
The control master chip 105 adjusts the output to the control according to the voltage change of the voltage acquisition output terminals A DC
The signal magnitude of signal input part Cont processed, to control the first of the front end power circuit 101 the power supply output terminal OUT1, second
The output voltage values of power supply output terminal OUT2；And by the reference signal input terminal PWM_REF to the rear end linear constant current
Circuit 103 inputs the constant current reference voltage VREF。
The control master chip 105 is additionally operable to the on off state according to the LED light string to the Regulate signal input terminal
The level value of Cont_S synchronizes adjustment, including：When linear to the rear end by the reference signal input terminal PWM_REF
Constant-current circuit 103 inputs the constant current reference voltage VREFDuring so that LED light string being opened, by the Regulate signal input terminal Cont_
The magnitude of voltage of S adjusts so that the switching tube QB3 is turned on, when by the reference signal input terminal PWM_REF to the rear end
Linear constant current circuit 103 inputs the constant current reference voltage VREFDuring so that LED light string turning off, by the electricity of the adjusting input terminal
Level values adjust so that the switching tube QB3 ends.
Specifically, when the control master chip 105 detects that the voltage acquisition output terminals A DC and the reference signal are defeated
When entering to hold the voltage difference of PWM_REF to be more than default threshold value, the control master chip 105 will export defeated to the control signal
Enter to hold the voltage signal duty cycle of Cont to reduce.When it is implemented, the control master chip 105 is built-in with analog-digital converter, use
Digital signal is converted in the voltage signal for accessing the control master chip 105.Obtained from voltage acquisition output terminals A DC collections
Voltage signal first pass around the conversion of analog-digital converter after, obtain corresponding digital signal, then by controlling in master chip 105
Other processing units processing.
Since excessive input voltage value can influence the normal work of analog-digital converter, and the P points when closing LED light string
Magnitude of voltage easily causes the resistance between former connection analog-digital converter of the prior art to produce low current signal, so that
LED backlight produces glimmer phenomenon.Since the present embodiment is provided with voltage detecting circuit 104, can when turning off backlight electric power,
By controlling triode QB3 cut-offs to be moved back to so as to effectively separate the current signal of voltage detecting circuit 104 in LED light string,
Avoid the generation of " glimmer phenomenon ".
The present embodiment is defeated to control signal input Cont, the reference signal as a result of same control master chip
At the signal for entering to hold PWM_REF, the voltage acquisition output terminals A DC and Regulate signal input terminal tetra- terminals of Cont_S
Reason, therefore on the basis of previously described beneficial effect, further can be in real time according to reference signal input terminal PWM_REF
And the signal intensity of voltage acquisition output terminals A DC, and to control signal input Cont and Regulate signal input terminal Cont_S
Corresponding control signal is sent, therefore the beneficial effect that the change rapidly to LED light string operating voltage is responded can be reached.
Embodiment 7
Further, the embodiment of the present invention additionally provides a kind of television set, including：TV SKD, backlight LED light string,
And constant current and the backlight control circuit of any low-power consumption of 1~embodiment of embodiment 6 above.
The linear constant current and backlight control circuit are connected respectively with the TV SKD and the backlight LED light string,
For the operating voltage according to the backlight LED light string by incoming control signal, the power supply of the television set can opened
When, according to the operating voltage of the backlight LED light string, automatic adjusument supplies the TV SKD, the backlight LED light string
Voltage signal；When closing the power supply of the television set, shut-off flows through the electric current of the backlight LED light string.Wherein, it is linear permanent
Stream and backlight control circuit are formed with operation principle with described previously identical substantially, and details are not described herein.The television set is carrying
While the flexibility that high voltage is adjusted, LED power consumptions are reduced, improve the service life of LED and the overall performance of mainboard.
The above is the preferred embodiment of the present invention, it is noted that for those skilled in the art
For, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications are also considered as
Protection scope of the present invention.
Claims (29)
1. constant current and the backlight control circuit of a kind of low-power consumption, it is characterised in that including：Front end power circuit and rear end are linearly permanent
Current circuit；
The front end power circuit includes power supply circuit and feedback adjustment circuit；The power supply circuit supplies electricity output including first
End, the second power supply output terminal and feedback control end；The feedback adjustment circuit include feedback input end, control signal input and
Feedback signal output；The feedback input end is connected with the described second power supply output terminal, the feedback signal output and institute
State power supply circuit connection；The feedback adjustment circuit is according to the magnitude of voltage of the control signal input, to the feed back input
End received signal is adjusted to export feedback signal to the power supply circuit, so as to control the power supply circuit to described the
The magnitude of voltage of one power supply output terminal and the second power supply output terminal is adjusted；
The rear end linear constant current circuit is connected with the cathode of LED light string to be powered, for controlling output to the LED to be powered
The electric current of lamp string is constant current signal；The anode of the LED light string to be powered is connected with the described first power supply output terminal；
The rear end linear constant current circuit is equipped with a connection reference signal input terminal to access constant current reference voltage, and according to described
The connection of rear end linear constant current circuit described in the size ON/OFF of constant current reference voltage and the LED light string to be powered；
Linear constant-current circuit is drawn electric all the way with the LED light string junction to be powered by voltage detecting circuit in the rear
Pressure gathers output terminal to gather the voltage of the junction, and the voltage of the control signal input is adjusted according to collection result
Value；
The voltage detecting circuit is used for：When the company for detecting the rear end linear constant current circuit and the LED light string to be powered
When connecing conducting, the connection of the voltage acquisition output terminal and the junction is turned on；When detecting the rear end linear constant current circuit
When connection with the LED light string to be powered disconnects, the connection of the voltage acquisition output terminal and the junction is disconnected.
2. constant current and the backlight control circuit of low-power consumption as claimed in claim 1, it is characterised in that the voltage detecting circuit
Including diode and pull-up resistor, the cathode of the diode is connected to the cathode of the LED light string to be powered, and anode is connected to
One end of pull-up resistor, the other end access high level of pull-up resistor；It is defeated that the anode of the diode connects the voltage acquisition
Outlet, the high level of the pull-up resistor access are provided by the rear end linear constant current circuit.
3. constant current and the backlight control circuit of low-power consumption as claimed in claim 2, it is characterised in that the anode of the diode
The voltage acquisition output terminal is also connected by a resistance.
4. constant current and the backlight control circuit of low-power consumption as claimed in claim 2, it is characterised in that the anode of the diode
The voltage acquisition output terminal is also connected by another diode；The anode of another diode and the anode of the diode
Connection；The cathode of another diode is as the voltage acquisition output terminal.
5. constant current and the backlight control circuit of low-power consumption as claimed in claim 1, it is characterised in that the voltage detecting circuit
Including switching tube QB3, the input terminal of the switching tube QB3 connects the junction, and output terminal connects the voltage acquisition output terminal,
Control terminal connects a Regulate signal input terminal, by adjusting the magnitude of voltage of the Regulate signal input terminal, makes the rear end linear
Switching tube QB3 is turned on while constant-current circuit is turned on the connection of the LED light string to be powered, the rear end linear constant current circuit
Switching tube QB3 ends while connection with the LED light string to be powered disconnects；The voltage detecting circuit passes through the voltage
Collection output terminal detects the operating voltage of the LED light string to be powered, so as to control described in the feedback adjustment the regulation of electrical circuit
The output voltage of first power supply output terminal, the second power supply output terminal.
6. constant current and the backlight control circuit of low-power consumption as claimed in claim 5, it is characterised in that the voltage detecting circuit
Further include resistance RB19 and resistance RB20；
The output terminal of the switching tube QB3 is connected with one end of resistance RB19, and the other end of resistance RB19 is adopted as the voltage
Collect output end voltage collection output terminal；The control terminal of the switching tube QB3 is connected with one end of resistance RB20, and resistance RB20's is another
One end is as the Regulate signal input terminal.
7. constant current and the backlight control circuit of low-power consumption as claimed in claim 6, it is characterised in that the voltage detecting circuit
Further include switching tube QB4, resistance R21, resistance RB22 and resistance RB23；Wherein, one end of resistance R21 is connected to the junction
On, the other end is connected on the tie point of switching tube QB3 and resistance RB20；
The output terminal of the switching tube QB4 connects the other end of the resistance RB20；The input terminal of switching tube QB4 is connected to ground；
On the one hand the control terminal of switching tube QB4 is connected to ground by resistance RB22, on the other hand connect one end of resistance RB23, resistance
The other end of RB23 is as the Regulate signal input terminal.
8. constant current and the backlight control circuit of low-power consumption as claimed in claims 6 or 7, it is characterised in that the switching tube QB3
For triode or field-effect tube.
9. constant current and the backlight control circuit of low-power consumption as claimed in claim 7, it is characterised in that the switching tube QB4 is
Triode or field-effect tube.
10. constant current and the backlight control circuit of low-power consumption as claimed in claim 1, it is characterised in that the voltage detecting electricity
Road further includes a filter circuit of pressure-stabilizing；The filter circuit of pressure-stabilizing is connected between the voltage acquisition output terminal and ground；
The filter circuit of pressure-stabilizing includes zener diode, filter capacitor and filter resistance in parallel；And the zener diode
Cathode be connected on the voltage acquisition output terminal, the plus earth of the zener diode.
11. constant current and the backlight control circuit of low-power consumption as claimed in claim 1, it is characterised in that：The rear end linear constant current
Circuit includes comparing adjustment circuit and constant-current control circuit；The constant-current control circuit includes at least switching tube QB1 and control electricity
Road module；The relatively adjustment circuit includes operational amplifier, and the reverse input end of the operational amplifier connects the reference
Signal input part, positive input connection are grounded by constant current detection resistance, and the output terminal of the operational amplifier passes through described
Control circuit module connects the control terminal of the switching tube QB1；The input terminal of the switching tube QB1 and the LED light to be powered
The cathode connection of string, the output terminal of the switching tube QB1 are grounded by the constant current detection resistance.
12. constant current and the backlight control circuit of low-power consumption as claimed in claim 11, it is characterised in that：
When the switching tube QB1 is triode, the collector of the triode and one end of the LED light string to be powered connect
Connect, emitter is grounded by the constant current detection resistance, and base stage passes through the control circuit module and the operational amplifier
Output terminal connects；
When the switching tube QB1 is field-effect transistor, the drain electrode of the field-effect transistor and the LED light string to be powered
One end connection, source electrode is grounded by the constant current detection resistance, and grid is put by the control circuit module and the computing
The output terminal connection of big device.
13. constant current and the backlight control circuit of low-power consumption as claimed in claim 11, it is characterised in that：The constant current detection resistance
Mainly by resistance RB6, resistance RB7, resistance RB8 is in parallel with resistance RB9 forms.
14. constant current and the backlight control circuit of low-power consumption as claimed in claim 11, it is characterised in that：The operational amplifier
Normal phase input end is connected by resistance RB5 with the constant current detection resistance, and the output terminal of the switching tube is connected to the resistance
RB5 and the junction of the constant current detection resistance.
15. constant current and the backlight control circuit of low-power consumption as claimed in claim 11, it is characterised in that：The operational amplifier
Normal phase input end is also grounded by capacitance CB5.
16. constant current and the backlight control circuit of low-power consumption as claimed in claim 11, it is characterised in that：The relatively adjustment circuit
Further include a clamp diode；
The minus earth of the clamp diode；The anode of the clamp diode is connected with the output terminal of the switching tube.
17. constant current and the backlight control circuit of low-power consumption as claimed in claim 1, it is characterised in that：Only when the voltage acquisition
When the voltage for the junction that output terminal collects is greater than or equal to default threshold value, the control signal input is just adjusted
Magnitude of voltage, so that the first power supply output terminal, the output voltage of the second power supply output terminal are further adjusted, so that the junction
Voltage be less than default threshold value.
18. constant current and the backlight control circuit of low-power consumption as claimed in claim 1, it is characterised in that：Further include a control main core
Piece；
The control master chip is exported with the control signal input, the reference signal input terminal and the voltage acquisition
End connects respectively；
The control master chip adjusts the output to the control signal input according to the voltage change of the voltage acquisition output terminal
The signal magnitude at end, to control the output voltage of the first of the front end power circuit the power supply output terminal, the second power supply output terminal
Value；And the constant current reference voltage is inputted to the rear end linear constant current circuit by the reference signal input terminal.
19. constant current and the backlight control circuit of low-power consumption as claimed in claim 5, it is characterised in that further include a control master
Chip；
The control master chip and the control signal input, the reference signal input terminal, the voltage acquisition output terminal
And the Regulate signal input terminal connects respectively；
The control master chip adjusts the output to the control signal input according to the voltage change of the voltage acquisition output terminal
The signal magnitude at end, to control the output voltage of the first of the front end power circuit the power supply output terminal, the second power supply output terminal
Value；
Level value of the control master chip according to the on off state of the LED light string to be powered to the Regulate signal input terminal
Adjustment is synchronized, including：When inputting the constant current to the rear end linear constant current circuit by the reference signal input terminal
When reference voltage is so that LED light string is opened, the magnitude of voltage of the Regulate signal input terminal is adjusted so that the switching tube QB3 is led
It is logical, when inputting the constant current reference voltage so that LED to the rear end linear constant current circuit by the reference signal input terminal
When lamp string turns off, the level value of the adjusting input terminal is adjusted so that the switching tube QB3 ends.
20. the constant current of low-power consumption and backlight control circuit as described in claim 18 or 19, it is characterised in that as the control master
When chip detects that the voltage difference of the voltage acquisition output terminal and the reference signal input terminal is more than default threshold value, institute
Control master chip is stated to reduce the voltage signal duty cycle exported to the control signal input.
21. constant current and the backlight control circuit of low-power consumption as claimed in claim 20, it is characterised in that the control master chip bag
Analog-digital converter is included, for the voltage signal of the control master chip access to be converted to digital signal.
22. constant current and the backlight control circuit of low-power consumption as claimed in claim 1, it is characterised in that the power supply circuit includes
Power supply input circuit, switching power circuit, multiple-channel output transformer, LED power supply output circuits and main board power supply output circuit；
The power supply signal of access is transmitted to the multichannel by the power supply input circuit under the control of the switching power circuit
Export transformer；
The multiple-channel output transformer includes main winding and auxiliary winding；The main winding will be transmitted to after the power supply signal transformation
The main board power supply output circuit, and exported by the described second power supply output terminal；The auxiliary winding believes the power supply
The LED power supplies output circuit is transmitted to after number synchronous transformation, and is exported by the described first power supply output terminal；The master
The coil ratio of winding and the auxiliary winding is 1：N, N ＞ 0.
23. constant current and the backlight control circuit of low-power consumption as claimed in claim 1, it is characterised in that
The feedback adjustment circuit includes opto-coupled feedback unit, voltage stabilizing reference cell, voltage sampling unit and voltage-adjusting unit；
The opto-coupled feedback unit includes optocoupler, and the optocoupler includes the light emitting diode positioned at primary side and the light positioned at secondary is believed
Number converter, the signal input part of the light emitting diode connect the feedback input end by first resistor；The optical signal
The signal output part of converter connects the feedback signal output；
The voltage sampling unit includes the 4th resistance and the 5th electricity for the series connection being connected between the feedback input end and ground
Resistance；
The voltage stabilizing reference cell includes voltage stabilizing standard and is connected between the reference input and cathode of voltage stabilizing standard
Voltage stabilizing feedback circuit；The reference input of the voltage stabilizing standard, which is connected between the 4th resistance and the series connection of the 5th resistance, to be located,
Plus earth, cathode connect the signal output part of the light emitting diode；
The voltage-adjusting unit includes the 6th resistance, and one end of the 6th resistance is connected to the 4th resistance and the 5th electricity
Locate between resistance series connection, the other end connects the control signal input.
24. constant current and the backlight control circuit of low-power consumption as claimed in claim 23, it is characterised in that the voltage stabilizing feedback circuit
Including the first capacitance and 3rd resistor；
One end of first capacitance is connected on the cathode of the voltage stabilizing standard, one end string of the other end and 3rd resistor
Connection；The other end of 3rd resistor is connected on the reference input of the voltage stabilizing standard.
25. constant current and the backlight control circuit of low-power consumption as claimed in claim 23, it is characterised in that the voltage stabilizing feedback circuit
Including the second capacitance；
One end of second capacitance is connected on the cathode of the voltage stabilizing standard, and the other end is connected to the voltage stabilizing standard
Reference input on.
26. constant current and the backlight control circuit of low-power consumption as claimed in claim 23, it is characterised in that the voltage stabilizing feedback circuit
Including the first capacitance, 3rd resistor and the second capacitance；
One end of first capacitance is connected on the cathode of the voltage stabilizing standard, one end string of the other end and 3rd resistor
Connection；The other end of 3rd resistor is connected on the reference input of the voltage stabilizing standard；
One end of second capacitance is connected on the cathode of the voltage stabilizing standard, and the other end is connected to the voltage stabilizing standard
Reference input on.
27. constant current and the backlight control circuit of low-power consumption as claimed in claim 1, it is characterised in that the control signal input
The magnitude of voltage at end and the output voltage correspondence of the power supply output terminal of the power supply circuit are：The control signal input
When magnitude of voltage is per 1% duty cycle of stepping, the output voltage change 0.01V of the first power supply output terminal, and second power supply
The output voltage change 0.1V of output terminal.
28. constant current and the backlight control circuit of low-power consumption as claimed in claim 18, it is characterised in that the control signal input
Hold the voltage signal or PWM ripples that are 0V~3.3V for range of voltage values of input, the output voltage of the first power supply output terminal
Correspond to and be adjustable as 11.5V~12.5V, and the output voltage automatic adaptation of the second power supply output terminal.
29. a kind of television set, including TV SKD, backlight LED light string, and such as claim 1~28 any one of them
The constant current of low-power consumption and backlight control circuit；
The backlight control circuit is connected respectively with the TV SKD and the backlight LED light string, for described in opening
During the power supply of television set, according to the operating voltage of the backlight LED light string, automatic adjusument supplies the TV SKD, institute
State the voltage signal of backlight LED light string；When closing the power supply of the television set, simultaneously turn off and flow through the backlight LED light string
Electric current.
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| CN104253954B (en) * | 2014-09-17 | 2017-11-03 | 广州视源电子科技股份有限公司 | The constant current of low-power consumption and backlight control circuit and television set |
| CN105163472B (en) * | 2015-10-30 | 2017-09-05 | 沈阳鼎越节能科技有限公司 | The processing of PWM ripples and constant-current control circuit |
| CN105764185B (en) * | 2016-03-18 | 2017-12-12 | 深圳Tcl数字技术有限公司 | Exchange driving mixing light adjusting circuit and television set |
| CN109982014B (en) * | 2019-04-22 | 2023-09-29 | 重庆惠科金扬科技有限公司 | Driving circuit and television |
| CN110445385A (en) * | 2019-07-30 | 2019-11-12 | 深圳创维－Rgb电子有限公司 | Separate television power supply system and separate television |
| CN112711285A (en) * | 2020-12-22 | 2021-04-27 | 深圳市艾尔曼医疗电子仪器有限公司 | Programmable high-voltage reference unit circuit and high-voltage reference source |
| CN113629801B (en) * | 2021-07-15 | 2023-01-17 | 深圳天德钰科技股份有限公司 | Power supply device |
| CN114204653B (en) * | 2022-02-18 | 2022-07-19 | 深圳市创芯微微电子有限公司 | Zero-power-consumption linear charging circuit |
| CN114675075A (en) * | 2022-04-15 | 2022-06-28 | 哈尔滨理工大学 | Weak current detection device |
| CN116633133B (en) * | 2023-07-21 | 2024-05-03 | 泉州艾奇科技有限公司 | Constant-current voltage stabilizing circuit |
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| KR101869681B1 (en) * | 2010-08-20 | 2018-06-21 | 가부시키가이샤 한도오따이 에네루기 켄큐쇼 | Lighting device |
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| CN102711321A (en) * | 2012-05-04 | 2012-10-03 | 福建捷联电子有限公司 | Light emitting diode driving circuit |
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