CN109217666A - ON-OFF control circuit and method, switch power supply system - Google Patents
ON-OFF control circuit and method, switch power supply system Download PDFInfo
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- CN109217666A CN109217666A CN201811393532.0A CN201811393532A CN109217666A CN 109217666 A CN109217666 A CN 109217666A CN 201811393532 A CN201811393532 A CN 201811393532A CN 109217666 A CN109217666 A CN 109217666A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
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Abstract
Present invention discloses a kind of ON-OFF control circuit and method, switch power supply system, the ON-OFF control circuit includes turn-on time control circuit, turn-off time control circuit, logic circuit；Logic circuit is exported to generate switch control signal gate according to the output signal of turn-on time control circuit, turn-off time control circuit to switch, the turn-on and turn-off of control switch；The logic circuit is after the predetermined ratio that this switch OFF duration reaches upper period shutdown duration, the switch control signal gate of ability output control switch conducting.ON-OFF control circuit proposed by the present invention and method, switch power supply system, the blanking time can be made no longer fixed, it can be in different occasions, or system it is unstable when automatic adjusument switch conduction point time, the adjacent switch period can be controlled more stable, it effectively avoids switch periods mutation and inductive current from entering CCM mode in earlier stage, realizes the stability contorting to output.
Description
Technical field
The invention belongs to electronic circuit technology fields, and in particular to a kind of ON-OFF control circuit and method, Switching Power Supply system
System.
Background technique
Fig. 1 is a low level buck circuit topology schematic diagram, and low level buck circuit includes a low-side switch Q, passes through control
The turn-on and turn-off of switch Q are made, control flows through the electric current of load LED to drive LED.When switch Q conducting, power supply, LED, electricity
Feel L and switch Q and form current path, electric current rises.When switch Q shutdown, LED, inductance L and diode D-shaped at current path,
Electric current decline.It is general that the signal that inductance L electric current drops to zero is detected by demagnetization detection circuit 10, obtain ZCD (zero current inspection
Survey) signal, interim, switch Q conducting is carried out in ZCD signal.When the electric current for flowing through switch Q meets condition, i.e. detection signal FB is full
When sufficient predetermined condition, switch Q shutdown.This control mode can be described as critical current mode (BCM), alternatively referred to as quasi-resonance control
System；There is also similar control modes in some other switch circuit topology (such as isolation flyback power supply topology).
Fig. 2 is the control waveform diagram of a low level buck circuit；The waveform diagram of Fig. 2 corresponds to above-mentioned control mode, waveform difference
Control signal gate, ZCD signal of corresponding inductive current IL, switch Q.It, can but sometimes due to the false triggering of ZCD signal
It can will lead to and be connected within the short time after switch Q shutdown, just be misleaded so that not yet arriving zero in inductive current IL, and
It is not the conducting (see the dotted line in Fig. 2) when inductive current IL becomes zero, so that system enters continuous current mode (CCM),
It exports out of hand.
Therefore, it is necessary to take measures to prevent this too early conducting.A kind of control mode be switch control signal Gate by
After high level becomes low level, the blanking time (as shown in Figure 3) of a set time length is set.During this period of time, it switchs
It will not be misled into logical.However, when system exists and interferes, especially for this topology of isolated flyback sourse, Huo Zheduo
In the presence of road power sources in parallel interferes with each other or when input voltage changes greatly, by the way that the blanking time of set time is arranged very
It tends not to play the role of when more (such as when underfrequency) good.
It can be seen that the adaptability of existing ON-OFF control circuit is not strong, it is not applied for a variety of different occasions.Such as not
The occasion of same input and output voltage or some occasions that there is interference may cause and disappear if the inductive current decline stage is longer
The hidden time is too short, not can avoid and enters CCM mode when electric current is larger, makes to export out of hand.Inductive current is declined
Stage shorter occasion, the blanking time short triggering that can extend switch conduction point make poor system performance.
In addition, (such as system EMC interference is strong or more in the occasion of system context complexity for existing ON-OFF control circuit
When the power sources in parallel of road), there is also Similar Problems, by be arranged blanking time of set time many times (such as frequency mistake
When low) often earlier stage cannot play a role after shut-off, so that entering CCM mode in earlier stage, output is allowed to lose
Control.
In view of this, nowadays there is an urgent need to design a kind of switch control mode, to overcome existing for existing control mode
Drawbacks described above.
Summary of the invention
The present invention provides a kind of ON-OFF control circuit and method, switch power supply system, it can be achieved that stability contorting to output.
In order to solve the above technical problems, according to an aspect of the present invention, adopting the following technical scheme that
A kind of ON-OFF control circuit, the ON-OFF control circuit include:
Turn-on time control circuit, to generate the first control signal of control switch conducting；
Turn-off time control circuit, to generate the second control signal of control switch shutdown；
Logic circuit, input terminal are separately connected the output of the turn-on time control circuit and turn-off time control circuit
End, to generate switch control signal gate according to the output signal of turn-on time control circuit, turn-off time control circuit, and
Output extremely switchs, the turn-on and turn-off of control switch；
The logic circuit, could be defeated after the predetermined ratio that this switch OFF duration reaches upper period shutdown duration
The switch control signal gate of control switch conducting out.
" ability " expression is allowed to, and is immediately performed subsequent action without indicating whether.
As one embodiment of the present invention, the ON-OFF control circuit further includes third control signal generating circuit；
The input terminal of the third control signal generating circuit receives the switch control signal gate, obtains a upper period
Switch OFF duration；
The output end of the third control signal generating circuit connects logic circuit, to logic circuit output third control letter
Number, with the state of the switch control signal gate of control logic circuit output；
After the predetermined ratio that this switch OFF duration reaches upper period shutdown duration, third controls signal and generates electricity
Lu Caixiang logic circuit, which is sent, allows the third of switch conduction to control signal, and logic circuit ability output control switch conducting is opened
Close control signal gate.
As one embodiment of the present invention, the turn-off time control circuit is also to send zero electricity to logic circuit
Stream detection signal ZCD, zero current detection signal ZCD is with third control signal by connecting the logic circuit with door.
As one embodiment of the present invention, the third control signal generating circuit includes a frequency locking circuit, frequency locking
Circuit receives the switch control signal gate, to obtain the turn-off time of a upper cycle switch, obtains a upper period with this
Switch OFF duration；
The frequency locking circuit generated third based on the switch OFF duration in a upper period and controls signal, in this switch OFF
Duration just sends the first state for allowing switch conduction after reaching the predetermined ratio of period shutdown duration to logic circuit
Third controls signal；When the switch is closed, the frequency locking circuit is by the level control of third control signal for different from the first shape
Second state of state.
As one embodiment of the present invention, the turn-on time control circuit includes error amplifier, compensation network
With turn-on time modulation circuit；Error amplifier, compensation network, turn-on time modulation circuit are sequentially connected；The error amplification
The inverting input terminal of device connects current feedback signal, and the normal phase input end of error amplifier connects threshold signal Vth, error amplification
Device amplifies current feedback signal FB and the error of threshold signal Vth；The output end of the error amplifier connects compensation
Network exports amplified signal to compensation network；Compensation network receives the amplified signal of error amplifier, and generates benefit
Signal is repaid, the thermal compensation signal of generation is sent to the turn-on time modulation circuit；The turn-on time modulation circuit is used for will
The thermal compensation signal and sawtooth signal that compensation circuit generates are compared, and the result after comparison is exported to the logic circuit；
Alternatively, the turn-on time control circuit includes a comparison circuit, when output current feedback signal FB touches a threshold
When threshold voltage, the trigger set that the logic circuit includes, switch OFF.
As one embodiment of the present invention, the third control signal generating circuit is as turn-off time control circuit
A part；The turn-off time control circuit include the second logic circuit, frequency locking circuit and with door；
The output end of the input terminal connection demagnetization detection circuit of second logic circuit, is exported based on demagnetization detection circuit
Signal generate zero current detection signal ZCD, and zero current detection signal ZCD is exported to the input terminal with door；
The input terminal of the frequency locking circuit connects the switch control signal gate, the output end connection of frequency locking circuit and door
Input terminal；It is described to connect the logic circuit with the output end of door.
As one embodiment of the present invention, the logic circuit includes trigger, the turn-on time control circuit
Including error amplifier, compensation network and turn-on time modulation circuit；
The output signal of the turn-on time modulation circuit is input to the reset terminal R of trigger, the turn-off time control
The output signal of circuit is input to the set end S of trigger.
As one embodiment of the present invention, the frequency locking circuit is to export frequency locking signal A；Switch control signal
Gate can only be that effective state of value could increase in frequency locking signal A, be switched to switch-turn-ON states；
For the frequency locking circuit after meeting this switch OFF duration T1 >=K*T0, control frequency locking signal A is virtual value shape
State；Wherein, K is setting constant, and T0 is to switch upper period shutdown duration.
As one embodiment of the present invention, during frequency locking signal A is high level state, if zero current detection signal
There is high level pulse in ZCD, and the logic circuit control switch control signal gate is got higher by low, for switch, inductance to be connected
Electric current IL is begun to ramp up；When switch control signal gate is by low get higher, the frequency locking circuit control frequency locking signal A becomes low electricity
It is flat.
A kind of switch power supply system, the switch power supply system include switching circuit and above-mentioned ON-OFF control circuit；
The switching circuit includes switch and inductance, and ON-OFF control circuit is by the turn-on and turn-off of control switch to inductance
In electric current controlled, and then control load in electric current.
As one embodiment of the present invention, the switching circuit be low level buck circuit, low level buck-boost circuit,
Inverse-excitation type voltage conversion circuit, any one in booster circuit.
A kind of method of controlling switch, comprising:
The switch control signal gate of control switch conducting is received, a upper cycle switch is obtained and turns off duration；
Judge whether this switch OFF duration reaches the predetermined ratio of period shutdown duration, if reached, logic
The switch control signal gate of circuit ability output control switch conducting.
As one embodiment of the present invention, opening for control switch conducting is received using third control signal generating circuit
Control signal gate is closed, so that obtaining a upper cycle switch turns off duration；
Judge whether this switch OFF duration reaches the predetermined ratio of period shutdown duration, if reached, third
Controlling signal generating circuit and sending to logic circuit allows the third of switch conduction to control signal；
The state of logic circuit combination zero current detection signal ZCD and third control signal, export corresponding switch control
Signal gate.
The beneficial effects of the present invention are: ON-OFF control circuit proposed by the present invention and method, switch power supply system can make
Blanking time is no longer fixed, can (such as different input voltage vins or different output electric currents need in different occasion
Ask) or system it is unstable when automatic adjusument switch conduction point time, the adjacent switch period can be controlled more steady
It is fixed, it effectively avoids switch periods mutation and inductive current from entering CCM mode in earlier stage, realizes the stability contorting to output.
Detailed description of the invention
Fig. 1 is the topological schematic diagram of existing low level buck circuit.
Fig. 2 is the control waveform diagram of existing low level buck circuit.
Fig. 3 is the control waveform diagram that the blanking time is arranged in existing low level buck circuit.
Fig. 4 is the circuit diagram of the switching circuit of switch power supply system in one embodiment of the invention.
Fig. 5 is the circuit diagram of ON-OFF control circuit in one embodiment of the invention.
Fig. 6 is the circuit diagram that switching circuit is low level buck circuit in one embodiment of the invention.
Fig. 7 is the circuit diagram of ON-OFF control circuit in one embodiment of the invention.
Fig. 8 is the circuit diagram of the compensation network of ON-OFF control circuit in one embodiment of the invention.
Fig. 9 is the control waveform diagram of ON-OFF control circuit in one embodiment of the invention.
Specific embodiment
The preferred embodiment that the invention will now be described in detail with reference to the accompanying drawings.
For a further understanding of the present invention, the preferred embodiment of the invention is described below with reference to embodiment, still
It should be appreciated that these descriptions are only further explanation the features and advantages of the present invention, rather than to the claims in the present invention
Limitation.
Just for several typical embodiments, the present invention is not limited merely to the model of embodiment description for the description of the part
It encloses.Some technical characteristics in same or similar prior art means and embodiment, which are replaced mutually, also to be described in the present invention
In the range of protection.
" coupling " or connection in specification, also comprising being indirectly connected with, such as pass through some active devices both comprising being directly connected to
The connection that part, passive device or electrically-conducting medi carry out." multiple " refer to two or more.
Fig. 4 is the circuit diagram of switching circuit in one embodiment of the invention, and Fig. 5 is that control is switched in one embodiment of the invention
The circuit diagram of circuit processed.As shown in Figure 4, Figure 5, switching circuit 2 includes switching tube；ON-OFF control circuit 1 of the present invention includes:
Turn-on time control circuit 11, turn-off time control circuit 13, logic circuit 15.
First control signal of the turn-on time control circuit 11 to generate control switch conducting；Turn-off time control circuit
13 second control signal to generate control switch shutdown.The input terminal of logic circuit 15 is separately connected the turn-on time control
The output end of circuit 11 processed and turn-off time control circuit 13, to according to turn-on time control circuit 11, turn-off time control
The output signal of circuit 13 generates switch control signal gate, and exports to switch, the turn-on and turn-off of control switch.It is described to patrol
Circuit 15 is collected after the predetermined ratio that this switch OFF duration reaches upper period shutdown duration, ability output control switch is led
Logical switch control signal gate.
In one embodiment of this invention, the ON-OFF control circuit further includes third control signal generating circuit；It is described
The input terminal that third controls signal generating circuit receives the switch control signal gate, when obtaining the shutdown of a upper cycle switch
It is long.The output end of the third control signal generating circuit connects logic circuit 15, exports third control letter to logic circuit 15
Number, with the state of the switch control signal gate of control logic circuit output.Reached a upper period in this switch OFF duration
After the predetermined ratio for turning off duration, third controls signal generating circuit and just sends the third for allowing switch conduction to logic circuit 15
Control signal, the switch control signal gate of 15 ability output control switch conducting of logic circuit.
In one embodiment of this invention, the turn-off time control circuit is also to send zero current to logic circuit 15
Signal ZCD is detected, zero current detection signal ZCD is with third control signal by connecting the logic circuit 15 with door 135
(in combinable Fig. 7, Fig. 7, it is frequency locking circuit 133 that third, which controls signal generating circuit).
In one embodiment of this invention, please continue to refer to Fig. 5, the third control signal generating circuit includes a frequency locking
Circuit 133, frequency locking circuit 133 receive the switch control signal gate, so that the turn-off time of a upper cycle switch is obtained, with
This obtains a upper cycle switch and turns off duration.The frequency locking circuit 133 generated third based on the switch OFF duration in a upper period
Signal is controlled, is just sent to logic circuit 15 after the predetermined ratio that this switch OFF duration reaches upper period shutdown duration
The third of the first state (such as high level) of switch conduction is allowed to control signal；When the switch is closed, the frequency locking circuit 133 will
The level control that third controls signal is the second state (such as low level) different from first state, and the second state is when switch closes
Having no progeny does not allow the state of trigger switch conducting.
Fig. 6 is the circuit diagram of low level buck circuit in one embodiment of the invention；Referring to Fig. 6, of the invention one
In embodiment, switching circuit is low level buck circuit, and low level buck circuit includes switching tube Q, inductance L.Certainly, switching circuit
It can be other topologys, such as low level buck-boost circuit (buck-boost), inverse-excitation type voltage conversion circuit (flyback), liter
Volt circuit (boost) etc..
Fig. 7 is the circuit diagram of ON-OFF control circuit in one embodiment of the invention；Referring to Fig. 7, of the invention one
In embodiment, the turn-on time control circuit 11 includes error amplifier 111, compensation network 113 and turn-on time modulation electricity
Road 115；Error amplifier 111, compensation network 113, turn-on time modulation circuit 115 are sequentially connected.The error amplifier 111
Inverting input terminal connect current feedback signal, the normal phase input end of error amplifier 111 connects threshold signal Vth, and error is put
Big device 111 amplifies current feedback signal FB and the error of threshold signal Vth.The output end of the error amplifier 111
Compensation network 113 is connected, amplified signal is exported to compensation network 113.Compensation network 113 receives error amplifier 111
Amplified signal, and thermal compensation signal Vc is generated, the thermal compensation signal of generation is sent to the turn-on time modulation circuit 115.
The turn-on time modulation circuit 115 is for thermal compensation signal Vc and sawtooth signal M that compensation circuit 113 generates to be compared
(as shown in Figure 8) exports the result after comparison to the logic circuit 15.Fig. 8 is switch control in one embodiment of the invention
The compensation network of circuit and the circuit diagram of turn-on time modulation circuit 115；Referring to Fig. 8, in one embodiment of the invention
In, compensation network 113 includes capacitor C.
In another embodiment of the invention, the turn-on time control circuit 11 includes a comparison circuit, when output electricity
When stream feedback signal FB touches a threshold voltage, the trigger set that the logic circuit includes, switch OFF.
Please continue to refer to Fig. 7, in one embodiment of this invention, when the third control signal generating circuit is as shutdown
Between control circuit 13 a part (third control signal generating circuit can be frequency locking circuit 133)；The turn-off time control
Circuit 13 include the second logic circuit 131, frequency locking circuit 133 and with door 135.The input terminal of second logic circuit 131 connects
The output end for connecing demagnetization detection circuit 137 generates zero current detection signal ZCD based on the signal that demagnetization detection circuit 137 exports,
And zero current detection signal ZCD is exported to the input terminal with door 135.Entire demagnetization detection circuit 137 or demagnetization detection circuit
137 a part can be located at (a part of entire demagnetization detection circuit 137 or demagnetization detection circuit 137 in ON-OFF control circuit
It can be used as a part of ON-OFF control circuit)；Alternatively, demagnetization detection circuit may be alternatively located at, ON-OFF control circuit is outer (entirely to disappear
Magnetic sensor circuit 137 can also be not belonging to a part of ON-OFF control circuit and be independently arranged).In one embodiment of the invention
In, the demagnetization detection signal that demagnetization detection circuit 137 exports exports high level when inductive current is zero, is not in inductive current
It is low level when zero, which detects the rising edge of demagnetization detection signal, to generate ZCD pulse signal.The frequency locking electricity
The input terminal on road 133 connects the switch control signal gate, the input terminal of the output end connection and door 135 of frequency locking circuit 133；
The output end with door 135 connect the logic circuit 15.
In one embodiment of this invention, the logic circuit 15 includes trigger 151；The turn-on time modulation circuit
115 output signal is input to the reset terminal R of trigger 151, and the output signal of the turn-off time control circuit 13 is input to
The set end S of trigger 151, trigger 151 is for generating switch control signal (PWM or gate).
In one embodiment of this invention, the frequency locking circuit is to export frequency locking signal A；Switch control signal gate is only
It can be that effective state of value could increase in frequency locking signal A, be switched to switch-turn-ON states.
In one embodiment of this invention, the frequency locking circuit is after meeting this switch OFF duration T1 >=K*T0, control
Lockmaking frequency signal A is effective state of value；Wherein, K be setting constant (such as can choose as the numerical value between 80~95%, when
So it is also possible to other numerical value), T0 is to switch upper period shutdown duration.
In one embodiment of this invention, during frequency locking signal A is high level state, if zero current detection signal ZCD
There is high level pulse, exports high level pulse, 151 set of trigger, the logic circuit control switch control letter with door 135
Number gate is got higher by low, and for switch to be connected, inductive current IL is begun to ramp up；When switch control signal gate is by low get higher,
The frequency locking circuit control frequency locking signal A becomes low level.
Fig. 9 is the control waveform diagram of ON-OFF control circuit in one embodiment of the invention；Referring to Fig. 9, in the present invention
An embodiment in, the virtual value of frequency locking signal A appear in switch control signal gate shutdown period T0, T1, T2 it is latter half of
Point.Switch control signal gate can only be that effective state of value could increase in frequency locking signal A, be switched to switch-turn-ON states.Lock
T1 is related to upper 0 time span of a cycle T of gate at the beginning of frequency signal A virtual value.Timing when since the T1 period, t1=
K*T0, wherein K is constant, such as K can choose the numerical value between 80~95%.Frequency locking signal A is switch control signal gate
Opposite signal, and corresponding upper turn-off time in period length and ratio K product and generate the coincidence AND signal of signal.
During frequency locking signal A is high level state, there is high level pulse in zero current detection signal ZCD, then switchs control
Signal gate processed is got higher by low, and for switch to be connected, inductive current IL is begun to ramp up.When switch control signal gate is got higher by low
When, frequency locking signal A becomes low level.
Since switching frequency is higher, within the cracking time can automatic adjusument frequency locking signal initial time t1, have
It imitates and avoids being influenced in earlier stage by false triggering and switching tube Q is connected, effectively avoid switching the more early rank in inductive current decline
Section enters CCM mode.So that output is stablized.
The present invention discloses a kind of switch power supply system, and the switch power supply system includes switching circuit and switch control electricity
Road；Fig. 4 is the circuit diagram of switching circuit in one embodiment of the invention, and Fig. 5 is switch control electricity in one embodiment of the invention
The circuit diagram on road.As shown in Figure 4, Figure 5 and Figure 6, the switching circuit 2 includes switch and inductance, and ON-OFF control circuit 1 is logical
The turn-on and turn-off for crossing control switch Q control the electric current in inductance, and then control the electric current in load.
Fig. 6 is the circuit diagram of low level buck circuit in one embodiment of the invention；Referring to Fig. 6, of the invention one
In embodiment, switching circuit is low level buck circuit, and low level buck circuit includes switch Q, inductance L.Certainly, switching circuit can also
For other topologys, such as low level buck-boost circuit (buck-boost), inverse-excitation type voltage conversion circuit (flyback), boosting
Circuit (boost) etc..
The concrete composition of ON-OFF control circuit 1 can be found in the description above with respect to ON-OFF control circuit, and which is not described herein again.
The present invention discloses a kind of method of controlling switch, comprising:
The switch control signal gate of control switch conducting is received, a upper cycle switch is obtained and turns off duration；
Judge whether this switch OFF duration reaches the predetermined ratio of period shutdown duration, if reached, logic
The switch control signal gate that circuit could allow output control switch to be connected.
In one embodiment of this invention, the method for controlling switch includes:
The switch control signal gate that control switch conducting is received using third control signal generating circuit, thus on obtaining
One cycle switch turns off duration；
Judge whether this switch OFF duration reaches the predetermined ratio of period shutdown duration, if reached, third
Controlling signal generating circuit and sending to logic circuit allows the third of switch conduction to control signal；
The state of logic circuit combination zero current detection signal ZCD and third control signal, export corresponding switch control
Signal gate.
Detailed process in above each step, reference can be made to the above description in relation to ON-OFF control circuit component part is (special
It is not the relevant portion introduced in relation to Fig. 7 to Fig. 9), specific control is described in detail when introducing ON-OFF control circuit composition
Process processed, which is not described herein again.
In conclusion ON-OFF control circuit proposed by the present invention and method, switch power supply system, can make the blanking time no longer
Fixation, can be in different occasions (such as different input voltage vins or different output current needs) or system is not
The time of automatic adjusument switch conduction point, can control the adjacent switch period more stable, effectively avoid out when stablizing
It closes period discontinuity and inductive current and enters CCM mode in earlier stage, realize the stability contorting to output.
Description and application of the invention herein are illustrative, is not wishing to limit the scope of the invention to above-described embodiment
In.The deformation and change of embodiments disclosed herein are possible, the realities for those skilled in the art
The replacement and equivalent various parts for applying example are well known.It should be appreciated by the person skilled in the art that not departing from the present invention
Spirit or essential characteristics in the case where, the present invention can in other forms, structure, arrangement, ratio, and with other components,
Material and component are realized.Without departing from the scope and spirit of the present invention, can to embodiments disclosed herein into
The other deformations of row and change.
Claims (12)
1. a kind of ON-OFF control circuit, which is characterized in that the ON-OFF control circuit includes:
Turn-on time control circuit, to generate the first control signal of control switch conducting；
Turn-off time control circuit, to generate the second control signal of control switch shutdown；
Logic circuit, input terminal are separately connected the output end of the turn-on time control circuit and turn-off time control circuit,
To generate switch control signal gate according to the output signal of turn-on time control circuit, turn-off time control circuit, and it is defeated
Out to switch, the turn-on and turn-off of control switch；
The logic circuit could export control after the predetermined ratio that this switch OFF duration reaches upper period shutdown duration
The switch control signal gate of switch conduction processed.
2. ON-OFF control circuit according to claim 1, it is characterised in that:
The ON-OFF control circuit further includes third control signal generating circuit；
The input terminal of the third control signal generating circuit receives the switch control signal gate, obtains a upper cycle switch
Turn off duration；
The output end of the third control signal generating circuit connects logic circuit, controls signal to logic circuit output third,
With the state of the switch control signal gate of control logic circuit output；
After the predetermined ratio that this switch OFF duration reaches upper period shutdown duration, third controls signal generating circuit
Sending to logic circuit allows the third of switch conduction to control signal, the switch control of logic circuit ability output control switch conducting
Signal gate processed.
3. ON-OFF control circuit according to claim 2, it is characterised in that:
The turn-off time control circuit is also to send zero current detection signal ZCD, zero current detection signal to logic circuit
ZCD is with third control signal by connecting the logic circuit with door.
4. ON-OFF control circuit according to claim 2, it is characterised in that:
The third control signal generating circuit includes a frequency locking circuit, and frequency locking circuit receives the switch control signal gate,
To obtain the turn-off time of a upper cycle switch, upper cycle switch shutdown duration is obtained with this；
The frequency locking circuit generated third based on the switch OFF duration in a upper period and controls signal, in this switch OFF duration
The third for allowing the first state of switch conduction is just sent to logic circuit after reaching the predetermined ratio of period shutdown duration
Control signal；When the switch is closed, the frequency locking circuit is by the level control of third control signal for different from first state
Second state.
5. ON-OFF control circuit according to claim 2, it is characterised in that:
The a part of the third control signal generating circuit as turn-off time control circuit；The turn-off time control circuit
Including the second logic circuit, frequency locking circuit and with door；
The output end of the input terminal connection demagnetization detection circuit of second logic circuit, the letter based on the output of demagnetization detection circuit
Number zero current detection signal ZCD is generated, and zero current detection signal ZCD is exported to the input terminal with door；
The input terminal of the frequency locking circuit connects the switch control signal gate, and the output end of frequency locking circuit connects defeated with door
Enter end；It is described to connect the logic circuit with the output end of door.
6. ON-OFF control circuit according to claim 2, it is characterised in that:
The logic circuit includes trigger, and the turn-on time control circuit includes error amplifier, compensation network and conducting
Time-modulation circuit；
The output signal of the turn-on time modulation circuit is input to the reset terminal R of trigger, the turn-off time control circuit
Output signal be input to the set end S of trigger.
7. ON-OFF control circuit according to claim 6, it is characterised in that:
The frequency locking circuit is to export frequency locking signal A；Switch control signal gate can only be effective state of value in frequency locking signal A
It could increase, be switched to switch-turn-ON states；
For the frequency locking circuit after meeting this switch OFF duration T1 >=K*T0, control frequency locking signal A is effective state of value；Its
In, K is setting constant, and T0 is to switch upper period shutdown duration；
During frequency locking signal A is high level state, if there is high level pulse, the logic electricity in zero current detection signal ZCD
Way control switch control signal gate is got higher by low, and for switch to be connected, inductive current I L is begun to ramp up；Believe in switch control
When number gate is by low get higher, the frequency locking circuit control frequency locking signal A becomes low level.
8. ON-OFF control circuit according to claim 1, it is characterised in that:
The turn-on time control circuit includes error amplifier, compensation network and turn-on time modulation circuit；Error amplifier,
Compensation network, turn-on time modulation circuit are sequentially connected；The inverting input terminal of the error amplifier connects current feedback signal,
The normal phase input end of error amplifier connects threshold signal Vth, and error amplifier is by current feedback signal FB and threshold signal Vth
Error amplify；The output end of the error amplifier connects compensation network, and amplified signal is exported to compensation net
Network；Compensation network receives the amplified signal of error amplifier, and generates thermal compensation signal, and the thermal compensation signal of generation is sent to institute
State turn-on time modulation circuit；Thermal compensation signal and the sawtooth wave letter that the turn-on time modulation circuit is used to generate compensation circuit
It number is compared, the result after comparison is exported to the logic circuit；
Alternatively, the turn-on time control circuit includes a comparison circuit, when output current feedback signal FB touches threshold value electricity
When pressure, the trigger set that the logic circuit includes, switch OFF.
9. a kind of switch power supply system, which is characterized in that the switch power supply system includes switching circuit and claim 1
To 8 any ON-OFF control circuits；
The switching circuit includes switch and inductance, and ON-OFF control circuit is by the turn-on and turn-off of control switch in inductance
Electric current is controlled, and then controls the electric current in load.
10. switch power supply system according to claim 9, it is characterised in that:
The switching circuit is low level buck circuit, low level buck-boost circuit, inverse-excitation type voltage conversion circuit, in booster circuit
Any one.
11. a kind of method of controlling switch characterized by comprising
The switch control signal gate of control switch conducting is received, a upper cycle switch is obtained and turns off duration；
Judge whether this switch OFF duration reaches the predetermined ratio of period shutdown duration, if reached, logic circuit
The switch control signal gate of ability output control switch conducting.
12. method of controlling switch according to claim 11, it is characterised in that:
The switch control signal gate of control switch conducting is received using third control signal generating circuit, to obtain upper one week
Phase switch OFF duration；
Judge whether this switch OFF duration reaches the predetermined ratio of period shutdown duration, if reached, third control
Signal generating circuit is sent to logic circuit allows the third of switch conduction to control signal；
The state of logic circuit combination zero current detection signal ZCD and third control signal, export corresponding switch control signal
gate。
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| CN201811393532.0A CN109217666A (en) | 2018-11-21 | 2018-11-21 | ON-OFF control circuit and method, switch power supply system |
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