CN105119490B - Voltage x current dual output control circuit and constant voltage constant current power, display device - Google Patents
Voltage x current dual output control circuit and constant voltage constant current power, display device Download PDFInfo
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Abstract
The invention discloses a kind of voltage x current dual output control circuit, the voltage x current dual output control circuit includes voltage sampling unit, current sampling unit, output switching unit.The input of the voltage sampling unit is used for collection voltages signal, and the input of the current sampling unit is used to gather current signal, and the output end of the voltage sampling unit merges into public output with the output end of current sampling unit.The output switching unit exports the first control signal to the voltage sampling unit, and the second control signal is exported simultaneously to the current sampling unit, the voltage sampling unit and current sampling units alternately is controlled to work, that realizes the voltage signal of sampling and current signal replaces output.The invention also discloses a kind of constant voltage constant current power and its display device.The present invention realizes the alternating output of voltage and current signal, and when alternately exporting without the time difference.
Description
Technical Field
The invention relates to the field of control circuits, in particular to a voltage and current dual-output control circuit, a constant-voltage constant-current power supply and a display device.
Background
Along with the development of electronic equipment and the increase of complexity, more and more unit modules are arranged in the whole machine, so that a plurality of electronic equipment need various power supplies, and in order to meet the requirements of the electronic equipment on the power supply, people design an electronic equipment power supply system with voltage and current dual output. The power supply system for electronic devices with voltage and current dual output function usually needs a control circuit to realize the dual output function.
The existing voltage and current dual-output control circuit comprises a voltage output control circuit and a current output control circuit. When the voltage signal is required to be output, the voltage output control circuit is switched on, and the current output control circuit is switched off, so that the power supply system outputs the voltage signal. When the current signal is required to be output, the current output control circuit is switched on, and the voltage output control circuit is switched off, so that the power supply system outputs the current signal.
Although the circuit structure can realize the function of dual output of the voltage signal and the current signal, the voltage output control circuit and the current output control circuit in the circuit structure are independent, so that time difference exists in the process of alternately outputting the voltage signal and the current signal.
Disclosure of Invention
The invention mainly aims to provide a voltage and current dual-output control circuit, a constant-voltage constant-current power supply and a display device, and aims to realize that the voltage and current dual-output control circuit has no time difference in the process of alternately outputting sampled voltage and current signals.
In order to achieve the above object, the present invention provides a voltage-current dual-output control circuit, which includes a voltage sampling unit, a current sampling unit, and an output switching unit.
The input end of the voltage sampling unit is used for collecting voltage signals, the input end of the current sampling unit is used for collecting current signals, and the output end of the voltage sampling unit and the output end of the current sampling unit are combined into a common output end;
the output switching unit outputs a first control signal to the voltage sampling unit and simultaneously outputs a second control signal to the current sampling unit to control the voltage sampling unit and the current sampling unit to work alternately.
Preferably, the voltage sampling unit comprises a first resistor, a second resistor and a first switch module; the controlled end of the first switch module is connected with the output switching unit to receive the first control signal, the input end of the first switch module is connected with one end of the first resistor, and the output end of the first switch module is connected with one end of the second resistor; the other end of the first resistor is the input end of the voltage sampling unit, the connection node of the second resistor and the first switch module is the output end of the voltage sampling unit, and the other end of the second resistor is grounded.
Preferably, the first switch module includes a first NPN type triode, a second PNP type triode, and a third resistor; a base electrode of the first NPN type triode is a controlled end of the first switch module, an emitting electrode of the first NPN type triode is grounded, and a collecting electrode of the first NPN type triode is connected with one end of the third resistor; the other end of the third resistor is connected with the base electrode of a second PNP type triode, the emitting electrode of the second PNP type triode is the input end of the first switch module, and the collector electrode of the second PNP type triode is the output end of the first switch module.
Preferably, the voltage sampling unit further includes a fourth resistor and a fifth resistor; one end of the fourth resistor is an input end of the voltage sampling unit, the other end of the fourth resistor is connected with one end of the first resistor, and the other end of the first resistor is connected with an emitting electrode of the second PNP triode; one end of the fifth resistor is connected with a collector of the second PNP type triode, a connection node of the fifth resistor and the second PNP type triode is an output end of the voltage sampling unit, the other end of the fifth resistor is connected with one end of the second resistor, and the other end of the second resistor is grounded.
Preferably, the current sampling unit comprises a second switch module and the second resistor; the controlled end of the second switch module is connected with the output switching unit to receive the second control signal; the input end of the second switch module is the input end of the current sampling unit, the output end of the second switch module is connected with one end of the second resistor, the connection node of the second switch module and the second resistor is the output end of the current sampling unit, and the other end of the second resistor is grounded.
Preferably, the switch module comprises a first enhancement type NMOS tube; the grid electrode of the first enhancement type NMOS tube is the controlled end of the second switch module, the drain electrode of the first enhancement type NMOS tube is the input end of the second switch module, and the source electrode of the first enhancement type NMOS tube is the output end of the second switch module.
Preferably, the output switching unit includes: the first inversion module is used for receiving an external control signal and performing inversion processing on the external control signal to form a first control signal; the second inversion module is used for carrying out inversion processing on the first control signal to form a second control signal; and the output module is used for enhancing the driving capability of the second control signal.
Preferably, the voltage-current dual-output control circuit further comprises an adjusting unit; the input end of the adjusting unit is connected with the common output end so as to alternately input the voltage sampling signal and the current sampling signal, amplify the voltage sampling signal and the current sampling signal and then alternately output the amplified voltage sampling signal and the amplified current sampling signal through the output end of the adjusting unit.
In addition, in order to achieve the above object, the present invention further provides a constant voltage and constant current power supply, which includes a power supply circuit, a transformer, a constant voltage output circuit, a voltage limiting control circuit, a constant current output circuit, a power management chip and the above voltage and current dual output control circuit;
the output end of the power supply circuit is connected with the first input end of the transformer, the first output end of the transformer is connected with the input end of the constant voltage output circuit, and the second output end of the transformer is connected with the input end of the constant current output circuit.
The control end of the constant-voltage output circuit is connected with the voltage-limiting control circuit, the output end of the constant-voltage output circuit is connected with the input end of a voltage sampling unit of the voltage-current dual-output control circuit, and the output end of the constant-current output circuit is connected with the input end of a current sampling unit of the voltage-current dual-output control circuit;
the output end of the adjusting unit of the voltage and current dual-output control circuit is connected with the power management chip, and the power management chip is also connected with the input end of the power circuit and the second input end of the transformer respectively.
In addition, in order to achieve the purpose, the invention also provides a display device, which comprises a display screen, a machine core and the constant-voltage and constant-current power supply;
the output end of the constant-voltage output circuit of the constant-voltage constant-current power supply is further connected with the movement and used for providing working voltage for the movement, and the output end of the constant-voltage constant-current output circuit of the constant-voltage constant-current power supply is further connected with the display screen and used for providing working current for the display screen.
The invention provides a voltage and current dual-output control circuit which comprises a voltage sampling unit, a current sampling unit and an output switching unit. The input of voltage sampling unit is used for gathering voltage signal, the input of current sampling unit is used for gathering current signal, voltage sampling unit's output and current sampling unit's output merge into an output. The output switching unit simultaneously generates a first control signal and a second control signal to control the voltage sampling unit and the current sampling unit to work alternately, so that the alternate output of the sampled voltage signal and the sampled current signal is realized. Because the output end of the voltage sampling unit and the output end of the current sampling unit in the voltage and current dual-output control circuit are combined into one output end, the existing voltage output control circuit and the current output control circuit work independently, and the whole system needs two output ends, the voltage and current dual-output control circuit has the characteristic of simple circuit structure compared with the prior art.
Drawings
FIG. 1 is a schematic diagram of functional modules of a constant voltage and constant current power supply according to the present invention;
FIG. 2 is a functional block diagram of a voltage-current dual-output control circuit according to the present invention;
FIG. 3 is a schematic diagram of a circuit structure of an output control unit in the voltage-current dual-output control circuit according to the present invention;
FIG. 4 is a schematic circuit diagram of an embodiment of a voltage sampling unit and a current sampling unit in a voltage-current dual-output control circuit according to the present invention;
FIG. 5 is a schematic circuit diagram of a voltage sampling unit and a current sampling unit in a voltage-current dual-output control circuit according to another embodiment of the present invention
FIG. 6 is a schematic circuit diagram of a constant voltage and constant current power supply according to an embodiment of the present invention;
FIG. 7 is a schematic circuit diagram of another embodiment of the constant voltage and constant current power supply of the present invention;
FIG. 8 is a functional block diagram of a display device according to the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1, the present invention provides a constant voltage and constant current power supply, including:
the power supply circuit 11, the transformer 12, the constant voltage output circuit 13, the constant current output circuit 14, the voltage and current dual-output control circuit 15, the power management chip 16 and the voltage limiting control circuit 17. The output end of the power circuit 11 is connected with the first input end of the transformer 12, the first output end of the transformer 12 is connected with the input end of the constant voltage output circuit 13, and the second input end of the transformer 12 is connected with the input end of the constant current output circuit 14.
The control end of the constant voltage output circuit 13 is connected with the voltage limiting control circuit 17, the output end of the constant voltage output circuit 13 is connected with the voltage signal acquisition end of the voltage and current dual-output control circuit 15, and the output end of the constant current output circuit 14 is connected with the current signal acquisition end of the voltage and current dual-output control circuit 15. The output end of the voltage and current dual-output control circuit 15 is connected with one end of the power management chip 16, and the power management chip is further connected with the input end of the power circuit 11 and the second input end of the transformer 12 respectively.
The power circuit 11, the transformer 12, the constant voltage output circuit 13, the voltage limiting control circuit 17, the voltage and current dual-output control circuit 15 and the power management chip 16 form a constant voltage power supply. The power circuit 11, the transformer 12, the constant current output circuit 14, the voltage and current dual-output control circuit 15 and the power management chip 16 form a constant current power supply.
The voltage and current dual-output control circuit 15 alternately collects the voltage signal output by the constant voltage output circuit 12 and the current signal output by the constant current output circuit 14 according to the voltage value of the control signal, and controls the constant voltage power supply and the constant current power supply to alternately work.
Specifically, when the constant voltage and constant current power supply is started, the power supply circuit 11 outputs a voltage to the transformer 12, the transformer 12 converts the voltage into two paths of signals, and transmits a first path of the two paths of signals to the constant voltage output circuit 13, and transmits a second path of the two paths of signals to the constant current output circuit 14.
When the voltage and current dual-output control circuit 15 collects the voltage signal output by the constant voltage output circuit 13 according to the voltage value of the control signal and transmits the sampling signal of the voltage signal to one end of the power management chip 16, the power management chip 16 controls the transformer 12 to output a constant voltage according to the sampling signal of the voltage signal, the constant voltage power supply is switched on, the constant current power supply is switched off, and the constant voltage and constant current power supply outputs a constant voltage.
When the voltage and current dual-output control circuit 15 collects the current signal output by the constant current output circuit 14 according to the voltage value of the control signal and transmits the sampling signal of the current signal to one end of the power management chip 16, the power management chip 16 controls the transformer 12 to output a constant current according to the sampling signal of the current signal, the constant current power supply is switched on, the constant voltage output circuit 13 outputs a voltage value under the control of the voltage limiting control circuit 17, and the constant voltage constant current power supply outputs a constant current.
The voltage and current dual-output control circuit 15 alternately collects the voltage signal output by the constant voltage output circuit 12 and the current signal output by the constant current output circuit 14 according to the voltage value of the control signal, so as to realize the function of alternately supplying power for constant voltage and constant current of the constant voltage and constant current power supply.
The constant voltage and constant current power supply provided by the invention comprises a constant voltage power supply and a constant current power supply. The on-off states of the constant voltage power supply and the constant current power supply are controlled by the voltage and current dual-output control circuit. Because the voltage and current dual-output control circuit only has one output end, no matter the constant voltage power supply works or the constant current power supply works, the power supply management chip controls the constant voltage and constant current power supply to output a constant voltage signal or a constant current signal according to a signal output by the voltage and current dual-output control circuit, and therefore the constant voltage and constant current power supply can continuously and alternately output the constant voltage signal and the constant current signal.
As shown in fig. 2, the voltage-current dual-output control circuit 15 includes a voltage sampling unit 151, a current sampling unit 152, and an output switching unit 150.
The input end of the voltage sampling unit 151 is used for collecting a voltage signal Uo, the input end of the current sampling unit 152 is used for collecting a current signal Io, and the output end of the voltage sampling unit 151 and the output end of the current sampling unit 152 are combined into a common output end OUT.
The output switching unit 150 outputs a first control signal to the voltage sampling unit 151 and simultaneously outputs a second control signal to the current sampling unit 152 to control the voltage sampling unit and the current sampling unit to alternately operate.
Specifically, as shown in fig. 3 and 4, the output switching unit 150 includes an eighth resistor R8, a ninth resistor R9, a sixth resistor R6, a third NPN transistor Q3, a tenth resistor R10, a seventh resistor R7, a fourth NPN transistor Q4, a fifth NPN transistor Q5, a sixth PNP transistor Q6, and an eleventh resistor R11.
One end of the eighth resistor R8 is configured to receive a PWM control signal, the other end of the eighth resistor R8 is connected to one end of the ninth resistor R9 and a base of the third NPN transistor Q3, the other end of the ninth resistor R9 is grounded, an emitter of the third NPN transistor Q3 is grounded, the third NPN transistor Q3 is connected to one end of the sixth resistor R6, and a connection node between the third NPN transistor Q3 and the sixth resistor R6 outputs a first control signalThe collector of the third NPN transistor Q3 is further connected to one end of the tenth resistor R10 and the base of the fourth NPN transistor Q4, and the other end of the tenth resistor R10 is grounded.
An emitter of the fourth NPN transistor Q4 is grounded, a collector of the fourth NPN transistor Q4 is connected to one end of the seventh resistor R7, another end of the seventh resistor R7 is connected to a power supply, a collector of the fourth NPN transistor Q4 is further connected to a base of the fifth NPN transistor Q5 and a base of the sixth PNP transistor Q6, a collector of the fifth NPN transistor Q5 is connected to a power supply, an emitter of the fifth NPN transistor Q5 is connected to an emitter of the sixth PNP transistor Q6, a collector of the sixth PNP transistor Q6 is grounded, an emitter of the fifth NPN transistor Q5 is further connected to one end of the eleventh resistor R11, and another end of the eleventh resistor R11 is configured to output the second control signal.
The first inverting module of the output switching unit 150 includes the sixth resistor R6 and the third NPN transistor Q3. The second inverting module of the output switching unit 150 includes the seventh resistor R7 and the fourth NPN transistor Q4. The output module of the output switching unit 150 includes the fifth NPN transistor Q5 and the sixth PNP transistor.
When the PWM control signal outputs a high level, the third NPN transistor Q3 is turned on, andthe voltage value of the first control signal is a difference between a power voltage and a voltage drop across the sixth resistor R6, and since there is no voltage dividing resistor between the emitter of the third NPN transistor Q3 and the ground and between the third NPN transistor Q3 and the sixth resistor R6, the difference between the power voltage and the voltage drop across the sixth resistor R6 is about the on-state voltage value of the third NPN transistor Q3, and the first inverting module of the output switching unit 150 outputs the first control signal as a low level voltageThe fourth NPN transistor Q4 is turned off, the fifth NPN transistor Q5 is turned on, the sixth PNP transistor Q6 is turned off, and the second inverting module of the output switching unit 150 outputs the second control signal as a high level PWMA.
Similarly, when the PWM control signal outputs a low level, the third NPN transistor Q3 is turned off, and the first inverting module of the output switching unit 150 outputs the first control signal as a high levelThe fourth NPN transistor Q4 is turned on, the fifth NPN transistor Q5 is turned off, the sixth PNP transistor Q6 is turned on, and the second inverting module of the output switching unit 150 outputs the second control signal as a low level PWMA.
The voltage sampling unit 151 and the current sampling unit 152 include a first resistor R1, a second PNP transistor Q2, a third resistor R3, a first NPN transistor Q1, a second resistor R2, and a first enhancement NMOS transistor N1.
One end of the first resistor R1 is an input end of the voltage sampling unit 151, and is used for collecting a voltage signal, the other end of the first resistor R1 is connected with the emitter of the second PNP type triode Q2, the base of the second PNP transistor Q2 is connected to one end of the third resistor R3, the other end of the third resistor R3 is connected to the collector of the first NPN transistor Q1, a base of the first NPN transistor Q1 is used for receiving the first control signal, an emitter of the first NPN transistor Q1 is grounded, the collector of the second PNP transistor Q2 is connected to one end of the second resistor R2 and the source of the first enhancement NMOS transistor N1, a connection node between the second PNP transistor Q2 and the second resistor R2 is an output terminal of the voltage sampling unit 151, and the other end of the second resistor R2 is grounded. The gate of the first enhancement mode NMOS transistor N1 is configured to receive the second control signal, and the drain of the first enhancement mode NMOS transistor N1 is an input terminal of the current sampling unit 152 and configured to collect a current signal.
The current sampling unit comprises a second resistor R2 and a first enhancement type NMOS transistor N1. The voltage sampling unit comprises a first resistor R1, a second PNP type triode Q2, a third resistor R3 and a first NPN type triode Q1.
Further, as shown in fig. 5, the voltage sampling unit 151 further includes a fourth resistor R4 and a fifth resistor R5.
One end of the fourth resistor R4 is an input end of the voltage sampling unit 151, and is configured to collect a voltage signal, the other end of the fourth resistor R4 is connected to one end of the first resistor R1, and the other end of the first resistor R1 is connected to an emitter of the second PNP transistor Q2. One end of the fifth resistor R5 is connected to the collector of the second PNP transistor Q2, the connection node between the fifth resistor R5 and the second PNP transistor Q2 is the output end of the voltage sampling unit 151, the other end of the fifth resistor R5 is connected to one end of the second resistor R2, and the other end of the second resistor R2 is grounded.
The first resistor and the second resistor are used for collecting voltage signals for the voltage sampling unit. The voltage value acquired by the voltage sampling unit can be dispersed by adding the fourth resistor and the fifth resistor, so that the voltage sampling signal output by the voltage sampling unit is more accurate.
When the PWM control signal outputs a high level, a PWM control circuitThe first control signalAnd outputting a low level, the first NPN transistor Q1 is turned off, the second PNP transistor Q2 is turned off, the first switching module of the voltage sampling unit 151 is turned off, and the voltage sampling unit 151 does not operate. The second control signal PWMA outputs a high level, the first enhancement NMOS transistor N1 is turned on, the second switch module of the current sampling unit 152 controls the input terminal of the current sampling unit 152 to collect a current signal, the current sampling unit obtains a sampling signal of the current signal through the second resistor R2, and the current sampling unit 152 outputs the sampling signal of the current signal.
When the PWM control signal outputs a low level, the first control signal outputs a high levelThe second control signal outputs a low level PWMA, the first enhancement NMOS transistor N1 is turned off, the second switch module of the current sampling unit 152 is turned off, and the current sampling unit 152 does not operate. The first NPN transistor Q1 is turned on, the second PNP transistor Q2 is turned on, the second control signal controls the first switch module of the voltage sampling unit 151 to be turned on, the first switch module of the voltage sampling unit 151 controls the input terminal of the voltage sampling unit 151 to collect a voltage signal, the voltage sampling module obtains a sampling signal of the voltage signal through the fifth resistor R5 and the second resistor R2, and the voltage sampling unit 151 outputs the sampling signal of the voltage signal.
The PWM control signal alternately outputs high and low levels, and the output switching unit 150 controls the voltage signal sampling unit 151 and the current signal sampling unit 152 to alternately operate according to the voltage value of the PWM control signal, so as to alternately output the voltage sampling signal and the current sampling signal.
The voltage sampling unit and the current sampling unit of the voltage and current dual-output control circuit provided by the invention share the common sampling resistor. The common resistor is always operated during the process that the output switching unit controls the voltage sampling unit and the current sampling unit to alternately operate. Therefore, the sampling voltage signal and the sampling current signal output by the voltage-current dual-output control circuit are continuous, and no time difference exists in the alternate output process.
Further, as shown in fig. 6, fig. 6 is a schematic diagram of a specific structure of the constant voltage and constant current power supply provided by the present invention.
The constant voltage and constant current power supply comprises a power supply circuit 11, a transformer 12, a constant voltage output circuit 13, a constant current output circuit 14, a voltage and current dual-output control circuit 15, a power supply management chip 16 and a voltage limiting control circuit 17.
The power circuit 11 comprises an alternating current power supply, an EMI filtering unit, a rectifying and filtering unit and a PFC power factor correction unit. The alternating current power supply is connected with the input end of the EMI filtering unit, the output end of the EMI filtering unit is connected with the input end of the rectifying and filtering unit, the output end of the rectifying and filtering unit is connected with the output end of the PFC power factor correction unit, and the output end of the PFC power factor correction unit is the output end of the power circuit 11. The transformer 12 comprises a first primary winding L1, a second primary winding L2, an iron core, a first secondary winding L3 and a second secondary winding L4, wherein the first primary winding L1 is connected in series with the second primary winding L2, and the first secondary winding L3 is connected in series with the second secondary winding L4. The end L11 of the first primary winding L1 is a first input end of the transformer 12, and the end L12 of the first primary winding L1 is grounded. The end L21 of the second primary winding L2 is a second input end of the transformer 12, and the end L22 of the second primary winding L2 is grounded. Both ends of the first secondary winding L3 are used as signal output terminals. The end L41 of the second secondary winding L4 is the first signal output end of the transformer 12, and the end L42 of the second secondary winding L4 is grounded.
The constant voltage output circuit 13 includes a fifth diode D5 and a second capacitor C2. The anode of the fifth diode D5 is connected to the first output terminal L41 of the transformer 12, the cathode of the fifth diode D5 is connected to one end of the second capacitor C2, and then led out to be used as the output terminal of the constant voltage output circuit 13, and the other end of the second capacitor C2 is grounded. The second capacitor C2 is used for filtering the output voltage of the constant voltage output circuit 13.
The constant current output circuit 14 includes a third capacitor C3, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fourth capacitor C4, a fifth capacitor D5, a first LED string LED1 … LED1n, and a second LED string LED2 … LED2 n. One end of the third capacitor C3 is connected to the L41 end of the second secondary winding L4 of the transformer 12, the other end of the third capacitor C3 is connected to the anode of the first diode D1 and the cathode of the second diode D2, the anode of the second diode D2 is grounded, the cathode of the first diode D1 is connected to one end of the fourth capacitor C4 and one end of the first LED light string, the other end of the fourth capacitor C4 is grounded, and the other end of the first LED light string is the output end of the constant current output circuit 14. The negative electrode of the third diode D3 is connected to the L42 end of the second secondary winding L4 of the transformer 12 and the positive electrode of the fourth diode D4, the positive electrode of the third diode D3 is grounded, the negative electrode of the fourth diode D4 is connected to one end of the fifth capacitor C5 and one end of the second LED light string, the other end of the fifth capacitor C5 is grounded, and the other end of the second LED light string is the output end of the constant current output circuit 14. The first diode D1, the second diode D2, the third diode D3 and the fourth diode D4 are used for rectification; the fourth capacitor C4 and the fifth capacitor C5 are used for filtering. When the voltage at the end L31 of the first secondary winding L3 of the transformer 12 is higher than the voltage at the end L32 of the first secondary winding L3, the first LED lamp string works, and when the voltage at the end L31 of the first secondary winding L3 of the transformer 12 is lower than the voltage at the end L32 of the first secondary winding L3, the second LED lamp string works.
The voltage and current dual-output control circuit 15 is the voltage and current dual-output control circuit 15. Further, the voltage and current dual-output control circuit 15 further includes a thirteenth resistor R13, a seventh NPN transistor Q7, an operational amplifier U4A, a first capacitor C1, and a twelfth resistor R12. A base of the seventh NPN transistor Q7 is connected to the standby signal PSON, an emitter of the seventh NPN transistor Q7 is grounded, a collector of the seventh NPN transistor Q7 is connected to one end of the thirteenth resistor R13, and another end of the thirteenth resistor R13 is connected to one end of the second resistor R2 and one end of the third resistor R3, respectively. The operational amplifier U4A, the first capacitor C1, and the twelfth resistor R12 constitute an adjusting unit of the voltage-current dual-output control circuit 15. The adjusting unit is configured to amplify the sampled voltage signal or current signal and input the amplified voltage signal or current signal to the power management chip 16.
The output end of the voltage and current dual-output control circuit 15 is formed by inputting a reference voltage Verf to an inverting input end of the operational amplifier U4A, connecting a non-inverting input end of the operational amplifier to the common output end, connecting and then leading out an output end of the operational amplifier U4A to one end of the twelfth resistor R12, connecting the other end of the twelfth resistor R12 to one end of the first capacitor C1, and connecting the other end of the first capacitor C1 to a non-inverting input end of the operational amplifier U4A.
The model of the power management chip 16 is TEA 1716. An optocoupler U2 and an eighteenth resistor R18 are further connected between the power management chip 16 and the voltage and current dual-output control circuit 15. The second signal end U22 of the optical coupler U2 is connected with the output end of the voltage and current dual-output control circuit 15, the first signal end U21 of the optical coupler U2 is connected with one end of an eighteenth resistor R18, the other end of the eighteenth resistor R18 is connected with the output end of the constant voltage output circuit 15, the third signal end U23 of the optical coupler U2 is grounded, and the fourth signal end U24 of the optical coupler U2 is connected with the twenty-first pin end SNSFB of the power management chip 16.
A second depletion type PMOS transistor N2, a third depletion type PMOS transistor N3 and a seventh capacitor C7 are connected between the power management chip 16 and the power circuit 11 and the transformer 12. The gate of the second depletion type PMOS transistor N2 is connected to the tenth pin terminal GATELS of the power management chip 16, the source of the second depletion type PMOS transistor N2 is grounded, the drain of the second depletion type PMOS transistor N2 is connected to one end of the seventh capacitor C7 and the source of the third depletion type PMOS transistor N3, respectively, the other end of the seventh capacitor C7 is connected to the L11 terminal of the first primary winding L1 of the transformer 12, the gate of the third depletion type PMOS transistor N3 is connected to the thirteenth pin terminal GATEHS of the power management chip 16, the drain of the third depletion type PMOS transistor N3 is connected to the output terminal of the power circuit 11, the seventh pin terminal GATEPFC of the power management chip 16 is connected to the input terminal of the power circuit 11, and the sixth pin terminal SUPIC of the power management chip 16 is connected to the L21 terminal of the second primary winding L2 of the transformer 11.
The voltage limiting control circuit 17 comprises a sixth diode D6, a fourth enhancement type NMOS transistor N4, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, a sixth capacitor C6, and a controlled rectifier IC 3. The cathode of the sixth diode D6 and the drain of the fourth enhancement type NMOS transistor N4 are connected to the output terminal of the constant voltage output circuit 13, the anode of the sixth diode D6 and the source of the fourth enhancement type NMOS transistor N4 are connected to a power supply, the gate of the fourth enhancement type NMOS transistor N4 is respectively connected to one end of the fourteenth resistor R14, one end of the sixteenth resistor R16 and the second signal terminal IC32 of the controlled rectifier IC3, the third signal terminal IC33 of the controlled rectifier IC3 is grounded, the first signal terminal IC31 of the controlled rectifier IC3 is connected to one end of the seventeenth resistor R17, one end of the sixth capacitor C6 and one end of the fifteenth resistor R15, the other end of the seventeenth resistor R17 is grounded, the other end of the sixth capacitor C6 is connected with the other end of the sixteenth resistor R16, the other end of the seventeenth resistor R17 and the other end of the fifteenth resistor R15 are connected to a power supply. The fifteenth resistor R15 and the seventeenth resistor R17 form a voltage divider circuit so that the voltage value output by the constant voltage output circuit 13 is smaller than the power supply voltage when the constant voltage power supply is turned off.
When in standby, the PWM control signal and the PSON standby signal are both low level, and the output switching unit of the voltage-current dual-output control circuit 15 outputs the first control signalAnd the second control signal PWMA output by the voltage-current dual-output control circuit 15 is at a high level. The first enhancement NMOS transistor N1 is turned off, the first NPN transistor Q1 is turned on, the second PNP transistor Q2 is turned on, and the voltage sampling unit of the dual-output control circuit 15 operates. At this time, the voltage sampling unit includes: the circuit comprises a fourth resistor R4, a first resistor R1, a third resistor R3, a fifth resistor R5, a second resistor R2, a first NPN type triode Q1 and a second PNP type triode Q2.
The common end of the voltage and current dual-output control circuit 15 outputs the voltage signal sampled by the voltage sampling unit to the adjusting unit of the dual-output control circuit 15, and the adjusting unit of the dual-output control circuit 15 amplifies the sampled voltage signal and outputs the amplified voltage signal. The amplified sampled voltage signal controls the power management chip 16 through the optocoupler U2, and the power management chip 16 enters a power saving mode, so that the output voltage of the constant voltage output circuit 13 of the constant voltage and constant current power supply becomes low, for example, 8V.
When the computer is started, the PSON standby signal is at a high level. The seventh NPN transistor Q7 is turned on, and the voltage sampling unit 151 of the voltage-current dual-output control circuit 15 includes: the circuit comprises a fourth resistor R4, a first resistor R1, a third resistor R3, a fifth resistor R5, a second resistor R2, a thirteenth resistor R13, a first NPN type triode Q1, a second PNP type triode Q2 and a seventh NPN type triode Q7.
When the PWM control signal outputs a high level, the output switching unit of the voltage-current dual-output control circuit 15 outputs the first control signalAnd is at a low level, the output switching unit of the voltage-current dual-output control circuit 15 outputs the second control signal PWMA at a high level. The voltage and current dual-output control circuit 15 works in a current sampling unit, the common end of the voltage and current dual-output control circuit 15 outputs a voltage signal sampled by the current sampling unit to the adjusting unit of the dual-output control circuit 15, and the adjusting unit of the dual-output control circuit 15 outputs the sampled voltage signal after amplification processing. The amplified sampled voltage signal controls the power management chip 16 through the optocoupler U2, and the power management chip 16 controls the constant current output circuit 14 of the constant voltage and constant current power supply to output a constant current for supplying power to the LED lamp string. At this time, since the voltage is kept constant after the LED string is turned on, the constant voltage output winding L4 of the transformer 12 is also kept at a constant voltage.
When the PWM control signal is at a low level, the output switching unit of the voltage-current dual-output control circuit 15 outputs the first control signalAnd the output switching unit of the voltage-current dual-output control circuit 15 outputs the second control signal PWMA to be at a low level. The voltage sampling unit of the voltage and current dual-output control circuit 15 works, the common end of the voltage and current dual-output control circuit 15 outputs the voltage signal sampled by the voltage sampling unit to the adjusting unit of the dual-output control circuit 15, and the adjusting unit of the dual-output control circuit 15 outputs the sampled voltage signal after amplification processing. The amplified sampled voltage signal controls the power management chip 16 through the optocoupler U2, and the power management chip 16 controls the constant voltage output circuit 13 of the constant voltage and constant current power supply to output a constant voltage. At this time, since the second control signal PWMA output by the output switching unit is at a low level, the first enhancement NMOS transistor N1 is turned off, and thus the LED string is extinguished.
The PWM control signal alternately outputs high and low levels, the constant voltage power supply 13 and the constant current power supply 14 alternately work, and the constant voltage and constant current power supply realizes the function of alternately supplying power by constant voltage and constant current.
In addition, as shown in fig. 7, fig. 7 is another specific structural schematic diagram of the constant voltage and constant current power supply provided by the present invention.
The difference between the present embodiment and the previous embodiment is that the power circuit 11 in the present embodiment includes an ac power supply, an EMI filter unit, and a rectifier filter unit; the output end of the alternating current power supply is connected with the input end of the EMI filter unit, the output end of the EMI filter unit is connected with the output end of the rectifier filter unit, and the output end of the rectifier filter unit is the output end of the power circuit 11 and is connected with the L11 end of the first primary winding L1 of the transformer 12.
The power management chip 16 is a flyback control chip. A second depletion type PMOS transistor N2 is connected between the transformer 12 and the power management chip 16, a gate of the second depletion type PMOS transistor N2 is connected to the first output end of the flyback control chip, a source of the second depletion type PMOS transistor N2 is grounded, a drain of the second depletion type PMOS transistor N2 is connected to the L12 end of the first primary winding L1 of the transformer 12, and a second output end of the flyback control chip is connected to the L21 end of the second primary winding L2 of the transformer 12.
The voltage and current dual-output control circuit has no time difference in the process of alternately outputting the sampled voltage signal and the sampled current signal, and the power management chip in the constant-voltage and constant-current power supply controls the constant-voltage and constant-current power supply to output the constant-voltage signal or the constant-current signal according to a signal output by the voltage and current dual-output control circuit, so that the constant-voltage and constant-current power supply provided by the invention has no time difference in the process of alternately outputting the constant-voltage signal and the constant-current signal. In conclusion, the invention solves the problem that the constant voltage and constant current power supply has no time difference in the process of alternately outputting the constant voltage signal and the constant current signal.
As shown in fig. 8, the present invention further provides a display device, where the display device includes a display screen, a core, and the constant voltage and constant current power supply, an output terminal of a constant voltage output circuit of the constant voltage and constant current power supply is further connected to the core, and is configured to provide a working voltage for the core, and an output terminal of a constant current output circuit of the constant voltage and constant current power supply is further connected to the display screen, and is configured to provide a working current for the display screen.
Specifically, when the display device is in a standby state, the constant current output circuit of the constant voltage and constant current power supply does not provide working current for the display screen, and the display screen is not bright. The output end of the constant voltage output circuit of the constant voltage and constant current power supply outputs a standby voltage to maintain the standby voltage of the movement.
When the display device is started and the constant-current power supply of the constant-voltage constant-current power supply works, the display screen obtains working current, the display screen is bright, and the output end of the constant-voltage output circuit of the constant-voltage constant-current power supply outputs a voltage value under the control of the voltage-limiting control circuit of the constant-voltage constant-current power supply so as to maintain the working voltage of the movement.
When the display device is started and the constant voltage power supply of the constant voltage and constant current power supply works, the movement obtains working voltage, the display screen does not have working current, and the display screen does not work.
The display device provided by the invention comprises a display screen, a machine core and the constant-voltage constant-current power supply. Because the constant voltage and constant current power supply has no time difference in the process of alternately outputting the constant voltage signal and the constant current signal, the display screen of the display device provided by the invention can not flicker when in work.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (9)
1. A voltage and current dual-output control circuit is characterized by comprising a voltage sampling unit, a current sampling unit and an output switching unit;
the input end of the voltage sampling unit is used for collecting voltage signals, the input end of the current sampling unit is used for collecting current signals, and the output end of the voltage sampling unit and the output end of the current sampling unit are combined into a common output end;
the output switching unit outputs a first control signal to the voltage sampling unit and simultaneously outputs a second control signal to the current sampling unit so as to control the voltage sampling unit and the current sampling unit to work alternately; wherein,
the voltage sampling unit comprises a first resistor, a second resistor and a first switch module; the controlled end of the first switch module is connected with the output switching unit to receive the first control signal, the input end of the first switch module is connected with one end of the first resistor, and the output end of the first switch module is connected with one end of the second resistor; the other end of the first resistor is an input end of the voltage sampling unit, a connection node of the second resistor and the first switch module is an output end of the voltage sampling unit, and the other end of the second resistor is grounded.
2. The voltage-current dual-output control circuit as claimed in claim 1, wherein the first switch module comprises a first NPN transistor, a second PNP transistor, and a third resistor; a base electrode of the first NPN type triode is a controlled end of the first switch module, an emitting electrode of the first NPN type triode is grounded, and a collecting electrode of the first NPN type triode is connected with one end of the third resistor; the other end of the third resistor is connected with the base electrode of a second PNP type triode, the emitting electrode of the second PNP type triode is the input end of the first switch module, and the collector electrode of the second PNP type triode is the output end of the first switch module.
3. The voltage-current dual-output control circuit as claimed in claim 2, wherein the voltage sampling unit further comprises a fourth resistor, a fifth resistor; one end of the fourth resistor is an input end of the voltage sampling unit, the other end of the fourth resistor is connected with one end of the first resistor, and the other end of the first resistor is connected with an emitting electrode of the second PNP triode; one end of the fifth resistor is connected with a collector of the second PNP type triode, a connection node of the fifth resistor and the second PNP type triode is an output end of the voltage sampling unit, the other end of the fifth resistor is connected with one end of the second resistor, and the other end of the second resistor is grounded.
4. The voltage-current dual-output control circuit as claimed in claim 1, wherein the current sampling unit comprises a second switch module, the second resistor; the controlled end of the second switch module is connected with the output switching unit to receive the second control signal; the input end of the second switch module is the input end of the current sampling unit, the output end of the second switch module is connected with one end of the second resistor, the connection node of the second switch module and the second resistor is the output end of the current sampling unit, and the other end of the second resistor is grounded.
5. The voltage-current dual-output control circuit as claimed in claim 4, wherein the second switch module comprises a first enhancement type NMOS transistor; the grid electrode of the first enhancement type NMOS tube is the controlled end of the second switch module, the drain electrode of the first enhancement type NMOS tube is the input end of the second switch module, and the source electrode of the first enhancement type NMOS tube is the output end of the second switch module.
6. The voltage-current dual-output control circuit as claimed in claim 1, wherein said output switching unit comprises:
the first inverting module is used for receiving an external control signal and inverting the external control signal to form the first control signal;
the second inverting module is used for inverting the first control signal to form a second control signal;
and the output module is used for enhancing the driving capability of the second control signal.
7. The voltage-current dual-output control circuit as claimed in claim 1, wherein the voltage-current dual-output control circuit further comprises an adjusting unit; the input end of the adjusting unit is connected with the common output end so as to alternately input the voltage sampling signal and the current sampling signal, amplify the voltage sampling signal and the current sampling signal and then alternately output the amplified voltage sampling signal and the amplified current sampling signal through the output end of the adjusting unit.
8. A constant voltage and constant current power supply, characterized in that the constant voltage and constant current power supply comprises a power supply circuit, a transformer, a constant voltage output circuit, a voltage limiting control circuit, a constant current output circuit, a power management chip and a voltage and current dual output control circuit as claimed in any one of claims 1 to 7;
the output end of the power supply circuit is connected with the first input end of the transformer, the first output end of the transformer is connected with the input end of the constant-voltage output circuit, and the second output end of the transformer is connected with the input end of the constant-current output circuit;
the control end of the constant-voltage output circuit is connected with the voltage-limiting control circuit, the output end of the constant-voltage output circuit is connected with the input end of a voltage sampling unit of the voltage-current dual-output control circuit, and the output end of the constant-current output circuit is connected with the input end of a current sampling unit of the voltage-current dual-output control circuit;
the output end of the adjusting unit of the voltage and current dual-output control circuit is connected with the power management chip, and the power management chip is also connected with the input end of the power circuit and the second input end of the transformer respectively.
9. A display device, comprising a display screen, a movement, and the constant voltage and constant current power supply of claim 8; the output end of a constant voltage output circuit of the constant voltage and constant current power supply is also connected with the movement and used for providing working voltage for the movement; the output end of the constant current output circuit of the constant voltage and constant current power supply is also connected with the display screen and used for providing working current for the display screen.
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| CN105813263B (en) * | 2016-04-22 | 2018-06-29 | 深圳创维－Rgb电子有限公司 | Switching Power Supply and television set |
| CN109149935B (en) * | 2018-09-07 | 2020-10-23 | 深圳市德赛微电子技术有限公司 | Control circuit for freely switching different working modes of switching power supply |
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