CN103368143B - Current mode switch power supply overpower-protection circuit - Google Patents
Current mode switch power supply overpower-protection circuit Download PDFInfo
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- CN103368143B CN103368143B CN201310333468.8A CN201310333468A CN103368143B CN 103368143 B CN103368143 B CN 103368143B CN 201310333468 A CN201310333468 A CN 201310333468A CN 103368143 B CN103368143 B CN 103368143B
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Abstract
Current mode switch power supply overpower-protection circuit, comprises power switch pipe current detecting end, load condition test side and pulse width modulating signal end, also comprises input over-power detection circuit, input normal power testing circuit, counting lock-in circuit.Input over-power detection circuit comprises the first decision circuitry, maximum duty cycle testing circuit and logical operation circuit.Adopt current mode switch power supply overpower-protection circuit of the present invention, the duty cycle of switching of power switch pipe and current sampling signal are monitored simultaneously, judges whether Switching Power Supply enters over-power condition, and close power switch pipe in time.Effectively prevent due to current sampling resistor abnormal state cause circuit to enter over-power condition after the generation of circuit deterioration extent that may occur.
Description
Technical field
The invention belongs to integrated circuit (IC) design field, relate to switch power integrated circuit design, particularly a kind of current mode switch power supply overpower-protection circuit.
Background technology
Switching Power Supply utilizes modern power electronics technology, the time ratio that control switch pipe turns on and off, and maintain a kind of power supply of regulated output voltage, Switching Power Supply is generally made up of pulse width modulation (PWM) control IC and MOSFET.Along with development and the innovation of power electronic technology, switch power technology is also constantly being innovated.At present, Switching Power Supply to be widely used nearly all electronic equipment with small-sized, light weight and high efficiency feature, is the indispensable a kind of power mode of current electronics and information industry develop rapidly.
According to the sample mode of control loop, Switching Power Supply can be divided into current mode switch power supply and voltage-type Switching Power Supply, voltage-type is only sampled to output voltage, signal after sampling is input in error amplifier, error amplifier is by amplifying the error of output voltage, produce COMP signal, utilize COMP analog voltage regulating impulse bandwidth modulation signals (PWM), thus control the duty cycle of switching of power switch pipe.Current mode switch power supply is except obtaining except COMP signal to output voltage sampling, also by the sampling regulating impulse bandwidth modulation signals (PWM) together with COMP signal to inductive current, thus the duty cycle of switching of power switch pipe is regulated, these two signals are normally input in PWM comparator by implementation together, PWM comparator output pwm signal.Current sample mode is more rapid to the adjustment of control loop, but stability is not enough.
Can be from power switch pipe sampling to the sample mode of inductive current, as shown in Figure 1, be that typical flyback former limit feedback detects Power converter system application structure block diagram.Power NMOS tube 102 conduction period is controlled at pwm signal, transformer 104 primary winding inductance controls the electric current rate of rise flowing through primary winding together with the direct current power source voltage Vdc after AC-input voltage rectification, this electric current flows through sampling resistor 103, and at the voltage signal that CS holds generation fixed slope to rise, after the magnitude of voltage that CS terminal voltage rises to set by current mode switch power control circuit 101 inside, PWM output signal controls switch-off power NMOS tube 102; Control power NMOS tube 102 blocking interval at pwm signal, transformer 104 secondary winding provides energy to output voltage together with the output rectifier diode 105 be attached thereto.
Between ground, sampling resistor 103 is in series with at the source electrode of power NMOS pipe 102, the electric current of power NMOS tube 102 flows through sampling resistor 103 and produces voltage signal CS and be input in control circuit, in Fig. 1, VDD, GND represent power end and the ground end of current mode switch power control circuit 101 respectively, INV represents output voltage feedback end, COMP represents the error-signal output of error amplifier, PWM represents the signal output of power switch pipe, and PWM end directly controls the duty cycle of switching of power switch pipe.
When CS holds the brownout detected, mean that the On current of power switch pipe is very little under normal circumstances, now adjustment pwm signal is opened power switch pipe with maximum duty cycle by control circuit, to increase Switching Power Supply power output.But in a practical situation, as follows may exist: sampling resistor 103 be shorted or resistance abnormal on the low side, because CS terminal voltage equals power switch tube current and sampling resistor resistance product, when sampling resistor resistance is minimum or be shorted, CS terminal voltage can not reflect the electric current flowing through power switch pipe normally, even if power switch tube current is large again, CS terminal voltage is still very low, control loop judges based on low CS voltage, make pwm signal control power switch pipe and increase duty ratio, easily occur because power switch pipe runs with maximum duty cycle for a long time under this over-power condition and can not normally be adjusted, cause a large amount of heating in the power switch pipe short time, power switch pipe or other partial destruction of circuit are caused even to explode.
Summary of the invention
For avoiding occurring, because the abnormal circuit that causes on the low side of CS terminal voltage enters over-power condition, damaging the technological deficiency of circuit, the invention discloses a kind of current mode switch power supply overpower-protection circuit.
This current mode switch power supply overpower-protection circuit; comprise power switch pipe current detecting end, load condition test side and pulse width modulating signal end; also comprise input over-power detection circuit, input normal power testing circuit, counting lock-in circuit, described input over-power detection circuit comprises:
First decision circuitry, its input is connected with power switch pipe current detecting end, judges power switch pipe current detecting
Whether whether terminal voltage lower than a preset value V1, and be greater than one lower than duration of this V1 and preset duration T1, and export the first judgement signal;
To power switch pipe, maximum duty cycle testing circuit, occurs that maximum duty cycle detects and exports maximum duty cycle detection signal;
With logical operation circuit, judge that signal and maximum duty cycle detection signal carry out and computing to first, export overpower detection signal;
Described input normal power testing circuit comprises:
Second decision circuitry, its input is connected with load condition test side with power switch pipe current detecting end, judges two
The voltage relationship of person, and export the second judgement signal as input normal power detection signal;
Described counting lock-in circuit comprises:
Counter, the input end of clock of counter is connected with pulse width modulating signal end, and clear terminal is connected with input normal power detection signal, and signal input part is connected with overpower detection signal, and described counter exports overpower confirmation signal;
State lock-in circuit (204), its input is connected with overpower confirmation signal, output exports overpower locking signal, be connected with power switch pipe ON-OFF control circuit, when overpower locking signal being detected, making power switch pipe ON-OFF control circuit control power switch pipe and being locked in closed condition.
Input over-power detection circuit is carried out comprehensive descision to maximum duty cycle and power switch pipe current detection voltage and is drawn whether enter over-power condition.And carry out Logic judgment with the comprehensive enter counter of the testing result of load condition test side, determine whether close power switch pipe.
The duty cycle of switching of power switch pipe and current sampling signal are monitored simultaneously, judges whether Switching Power Supply enters over-power condition, and close power switch pipe in time.Effectively prevent due to current sampling resistor abnormal state cause circuit to enter over-power condition after the generation of circuit deterioration extent that may occur.
Concrete, described first decision circuitry comprises a comparator and a delay circuit, and the DC level that the input of described comparator is V1 with power switch pipe current detecting end and magnitude of voltage is respectively connected, and the output of described comparator is connected with delay circuit input; Described delay circuit detects that comparator level changes, and exports first and judge signal after postponing to preset duration T1.
Preferably, described input normal power testing circuit also comprise the 3rd decision circuitry and or logical operation circuit, described 3rd decision circuitry judges soft start voltage SS and the power switch pipe current detecting terminal voltage of current mode switch power supply, and exports the 3rd and judge signal;
Described second judges that signal and the 3rd judges that signal all inputs or logical operation circuit carries out or computing, or the output signal of logical operation circuit is as input normal power detection signal.
The uncontrollable state of above-mentioned preferred implementation to the soft start stage judges, shields the mistake shut-off circuit situation in soft start stage.
Further, described 3rd decision circuitry is comparator, and the input of comparator is connected with soft start voltage SS and power switch pipe current detecting terminal voltage respectively.
Preferably, described second decision circuitry is comparator, and the input of comparator is connected with load condition test side and power switch pipe current detecting terminal voltage respectively.
In each preferred implementation of aforementioned employing comparator, described comparator also comprises input voltage regulation device, and input voltage regulation is normally made comparisons in the scope of result can make comparator by described input voltage regulation device.
Preferably, the overpower locking signal control switch power supply chip that described state lock-in circuit exports is closed and is made it no longer work.
Adopt current mode switch power supply overpower-protection circuit of the present invention, the duty cycle of switching of power switch pipe and current sampling signal are monitored simultaneously, judges whether Switching Power Supply enters over-power condition, and close power switch pipe in time.Effectively prevent due to current sampling resistor abnormal state cause circuit to enter over-power condition after the generation of circuit deterioration extent that may occur.
Accompanying drawing explanation
Fig. 1 illustrates the signal sampling schematic diagram of current mode switch power control circuit of the present invention;
Fig. 2 illustrates the schematic diagram of a kind of embodiment of current mode switch power supply overpower-protection circuit of the present invention;
Fig. 3 illustrates each signal each signal sequence relation when certain moment enters over-power condition in Fig. 2 circuit.
101: current mode switch power control circuit; 102: power NMOS tube; 103: sampling resistor; 104: transformer
105: export rectifier diode; 201: input over-power detection circuit; 202: input normal power testing circuit; 203: counter; 204: state latching circuit.
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail.
Current mode switch power supply overpower-protection circuit of the present invention; comprise power switch pipe current detecting end, load condition test side and pulse width modulating signal end; also comprise input over-power detection circuit 201, input normal power testing circuit 202, counting lock-in circuit, described input over-power detection circuit 201 comprises:
First decision circuitry, its input is connected with power switch pipe current detecting end, judges power switch pipe current detecting
Whether whether terminal voltage lower than a preset value V1, and be greater than one lower than duration of this V1 and preset duration T1, and export the first judgement signal;
To power switch pipe, maximum duty cycle testing circuit, occurs that maximum duty cycle detects and exports maximum duty cycle detection signal;
With logical operation circuit, judge that signal and maximum duty cycle detection signal carry out and computing to first, export overpower detection signal;
Described input normal power testing circuit comprises:
Second decision circuitry, its input is connected with load condition test side with power switch pipe current detecting end, judges two
The voltage relationship of person, and export the second judgement signal as input normal power detection signal;
Described counting lock-in circuit comprises:
Counter, the input end of clock of counter is connected with pulse width modulating signal end, and clear terminal is connected with input normal power detection signal, and signal input part is connected with overpower detection signal, and described counter exports overpower confirmation signal;
State lock-in circuit, its input is connected with overpower confirmation signal, export overpower locking signal end to be connected with power switch pipe ON-OFF control circuit, when overpower locking signal being detected, making power switch pipe ON-OFF control circuit control power switch pipe and being locked in closed condition.
Current mode switch power supply all detects power switch tube current and load condition and is fed back in control loop by detection signal.The duty ratio of signal to power switch pipe according to power switch pipe current detecting end and load condition test side regulates, and the voltage signal of load condition test side adjusts according to Switching Power Supply output loading state usually, when Switching Power Supply output loading is in light condition, the usual low voltage in load condition test side.
First decision circuitry is for judging power switch pipe current detection voltage value whether on the low side and lasting time on the low side, and export judged result, the specific implementation of the first decision circuitry can be a comparator and a delay circuit, the DC level that the input of comparator is V1 with power switch pipe current detecting end and magnitude of voltage is respectively connected, and the output of described comparator is connected with delay circuit input; Described delay circuit detects that comparator level changes, and exports first time of delay and judge signal after T1.Delay circuit can be counter, counts up to some cycles and export the signal after time delay from the upset edge of comparator.Delay circuit also can be capacitor charge and discharge circuit, and to capacitor charging or electric discharge from comparator upset, the level to electric capacity changes to default threshold value, the output signal upset of delay circuit.
In first decision circuitry, the DC level of V1 should a little more than null value, such as, within the scope of 10-200 millivolt value.
The state that maximum duty cycle testing circuit runs with maximum duty cycle for switch tube detects, the implementation of maximum duty cycle testing circuit both can directly be carried out duty ratio to power switch pipe signal and be detected judgement, also directly can judge from the M signal of control loop.
Such as to typical current mode switch power control circuit, comprise error amplifier and current comparator, error amplifier carries out exporting COMP signal after error is amplified to the output voltage of Switching Power Supply, this signal is input in current comparator together with current sampling signal, Switching Power Supply power switch pipe current waveform is continuous or discrete zigzag (respectively corresponding CCM and DCM pattern), when the peak of COMP signal higher than the sampled voltage signal of power switch tube current, current comparator exports and maintains overall height or full low level, now follow-up trigger triggers edge owing to lacking, therefore control switch pipe runs with maximum duty cycle.As long as maximum duty cycle testing circuit detects the output signal of above-mentioned current comparator, within a clock cycle, all keep COMP signal all higher than the output state that power switch pipe current sample voltage signal is corresponding, can think that now switching tube runs with maximum duty cycle state.
Can be one and door with logical operation circuit, also can increase other control logics or buffer stage, judge that signal and maximum duty cycle detection signal carry out and computing with logical operation circuit to first, export overpower detection signal.
The effect of input over-power detection circuit runs with maximum duty cycle when power switch pipe, and when inductive current sampled signal continues lower than V1, judge to think that now power switch pipe runs with over-power condition.The time T1 continued can determine according to the power output in practical application, and in general, power output increases, and time T1 should correspondingly extend.
Input normal power testing circuit utilizes the voltage of the second decision circuitry to inductive current sampled signal and load condition test side to judge, when load condition test side voltage is lower than inductive current sampled signal, namely exports input normal power detection signal.Obviously, the simplest implementation of the second decision circuitry is exactly comparator.
Be input in follow-up counter together with the overpower detection signal that input normal power detection signal COMP and aforesaid input over-power detection circuit export.The effect of input normal power detection signal is: if when detecting the COMP voltage that CS terminal voltage rises to higher than reflection output loading state in PWM duty cycle, that explanation is in normal operating state, even if now overpower detection signal is effective, do not think that the system that is in needs the over-power condition avoided, the false triggering occurring that in course of normal operation one time over-power condition causes once in a while can be avoided yet.
The input end of clock of counter is connected with pulse width modulating signal end, and clear terminal is connected with input normal power detection signal, and signal input part is connected with overpower detection signal, and described counter exports overpower locking signal.Serve as power detection signal to occur, along when arriving, to start with pulse width modulating signal PWM for counter clock counts, if count down to default number of cycles, then export overpower locking signal.If during counting, reset signal detected from clear terminal, then the count cycle is reset, count from newly.
The output loading state of load condition test side to Switching Power Supply detects, concerning current mode switch power supply, the DC voltage value of load condition test side (COMP) reflects output loading state, COMP magnitude of voltage is higher, then load is heavier, and corresponding power switch pipe duty ratio is larger, more may enter full duty ratio running status, COMP magnitude of voltage is lower, then reflect load lighter, the now corresponding reduction of power switch pipe duty ratio.
In the heavy duty stage, more big space rate also can be larger for the crest voltage of CS end, and that is under heavy condition, likely work maximum duty cycle state, but can come counter O reset, so can not false triggering be there is by detecting CS>V1 during this period.
In the underloading stage, the less duty ratio of CS end crest voltage also can be less, and that is under light condition, CS holds crest voltage to be likely less than V1, but now duty ratio does not reach maximum duty cycle, false triggering do not meet overpower detected state, so can not be there is.
The condition of overpower protection: A, CS<V1; B, detect and be operated in maximum duty cycle state; C, A, B two conditions must be detected in each PWM cycle whether meet; and recur until counter has calculated set periodicity just lock overpower protection state later; any one condition of above-mentioned two conditions does not meet during this period, all Circuit lock can not be fixed on over-power condition.
When output voltage does not reach preset value, load condition test side low voltage, now because output voltage is not enough, control loop may control power switch pipe and increase to the operation of full duty ratio, when V1 settings are higher or sampling resistor resistance is lower, aforesaid input over-power detection circuit may export input overpower detection signal.For above-mentioned this state, utilize input normal power detection signal to reset counter, the mistake avoiding overpower signal exports.As long as i.e. load condition test side low voltage lower than power switch pipe current sample voltage, then think and be now not in over-power condition.
Soft starting circuit is preferably combined with current mode switch power supply overpower-protection circuit by the present invention, shields the overpower wrong report that the soft start stage may occur.Concrete implementation is: described input normal power testing circuit also comprise the 3rd decision circuitry and or logical operation circuit, described 3rd decision circuitry judges relation between the soft start voltage SS of current mode switch power supply and power switch pipe current detecting terminal voltage, and exports the 3rd and judge signal;
Described second judges that signal and the 3rd judges that signal all inputs or logical operation circuit carries out or computing, or the output signal of logical operation circuit is as input normal power detection signal.
In prior art, for prevent Switching Power Supply startup stage output voltage too low cause power switch pipe for a long time completely duty ratio run the situation causing power switch pipe to generate heat to damage and occur, limit by increasing the voltage of soft starting circuit to load condition test side.Common soft start voltage SS curve to be the time from electronegative potential V2 rise with lower slope straight line or be divided into multiple step rise to a certain threshold value V3.The time risen to needed for this threshold value from electronegative potential is soft-start time, is generally Millisecond.In the soft start stage, soft start voltage detects voltage as load condition and is input to PWM comparator, and after the soft start stage completes, soft starting circuit no longer works, and SS voltage remains V3.
In the soft start stage, power switch pipe is in the nonfeedback control stage, the duty cycle of switching of power switch pipe does not rely on the feedback regulation of output voltage, the situation that full duty ratio is run may be there is, if now power switch pipe current detecting terminal voltage signal instant higher than soft start voltage, then think it is not over-power condition.
The soft start stage obtain the 3rd judge that signal and aforesaid second decision circuitry export second judge that signal is logically at the same level, as long as i.e. any one appearance of these two signals, not can think and be in over-power condition, use and logical circuit, to after these two signals and computing, obtain input normal power detection signal.The simplest implementation of 3rd decision circuitry is also comparator.
The value preferred value lower than soft start voltage SS usually of described V1, such as, when soft start voltage SS rises to threshold value V3 from electronegative potential V2, the voltage relationship between three is V1<V2<V3.
In the soft start stage, all soft start can be there is after powering on each time, in soft start-up process, output voltage does not generally all also reach set voltage, the voltage of COMP end is now maximum, also larger than the magnitude of voltage of V3, only in this way the conducting maximum voltage of soft start state CS end could be decided by soft start output voltage SS.If V2 voltage is arranged also less than V1 voltage; if so there is over-power condition in soft start-up process; due to V2<CS<V1; each PWM cycle is to counter O reset; but although now there occurs over-power condition counter can not calculate enough periodicities, so may there is occurring the phenomenon that over-power condition is not protected.Therefore arrange V1<V2<V3, avoid occurring above-mentioned condition, after the soft start stage enters over-power condition, CS voltage is only less than V1, then think and enter over-power condition.
Aforesaid with logical circuit and or logical circuit implementation have multiple, the logical relation those skilled in the art expressed also know, the wording that " with logic " and " or logic " is such is used in the present invention, be not limited to use this logical operation, by changing the output useful signal of each decision circuitry, there is corresponding logical operation formula, such as effectively become 0 effective by 1, those skilled in the art can be processed accordingly by simple logic variation relation, possible logical relation is no longer proper " with logic " and " or logic ", but this change does not depart from protection scope of the present invention.
Each comparator aforesaid, as in the embodiment of decision circuitry, can increase input voltage regulation device at the input of comparator, and such as divider resistance or output input are than the analog voltage follower being less than 1.Input voltage regulation is normally made comparisons in the scope of result can make comparator.Such as to the comparator as the second decision circuitry, if the voltage change range of power switch pipe current detecting end is 0-400 millivolt, and the voltage change range of load condition test side is 0.8-2.4V, direct input comparator can not provide correct result, be input to comparator input terminal again after can utilizing input voltage regulation device that the voltage scaled down of load condition test side is 100 to 300 millivolts.
After the overpower detection that counter exports being detected, the power switch pipe of state locking circuit controling switch power supply turns off, and avoids over-power condition to continue.Also can close whole Switching Power Supply makes it no longer work, and to save energy consumption, the Enable Pin of such as locking switch power supply chip is not enabled state, and partial switch power supply also has input power switching tube, also can close this switching tube and power supply is cut off.Until chip restarts the semaphore lock state in ability disarm state lock.
For better describing the present invention, the sequential relationship of each signal when illustrating that circuit enters over-power condition for Fig. 2 to 3.In Fig. 3, the position of each signal as shown in Figure 2, and judge that signal is high level effective, the COMP1 in Fig. 3, COMP2 represent two comparators respectively.
Wherein:
DMAX: maximum duty cycle signal;
CS: power switch pipe current detection signal;
CTRL1: the first judges signal;
CTRL1_D: the first judges signal delay signal;
CTRL2: the second judges signal;
CTRL3: the three judges signal;
CLEAR: input normal power detection signal;
LOCK: overpower locking signal;
COMP: load condition detection signal;
SS: soft start voltage.
In the T1 moment, detect that power switch pipe runs with maximum duty cycle, the upset of DMAX signal is high level, and subsequently in the T2 moment, CS voltage is reduced to lower than V1 value, and CTRL1 signal is turned to high level.After time delay, in the T3 moment, CTRL1_D signal is turned to high level.Now namely input over-power detection circuit after CTRL1_D and DMAX and computing and export overpower detection signal DIN, in the context of fig. 3, because DMAX signal is high level already, therefore DIN signal is actual almost overlaps with the CLTR1_D signal after time delay.After counter detects DIN signal, starting with pwm signal is that clock counts, suppose that the count cycle set is 4 power switch pipe switch periods, but in the T4 moment, because second judges that signal CTRL2 overturns, counter is cleared, therefore again count, until the T5 moment, meter full 4 clock cycle, overpower locking signal LOCK overturns.In Fig. 3 between T2 and the T3 moment, there is high level in CTRL3, but now due to counter and no count, therefore do not affect locking signal.
The waveform of pwm signal is not drawn in Fig. 3, in typical current mode switch power supply, the pass of CS signal and pwm signal is: when pwm signal is high, power switch pipe is opened, CS terminal voltage is non-vanishing, and those skilled in the art can obtain the approximate waveform of pwm signal from CS waveform.The sequential relationship of Fig. 3 to each signal has done concise and to the point signal, and to rise and fall wherein along triggering the regulation do not done in details, those skilled in the art can select arbitrarily rising edge or trailing edge as the triggering edge of counter etc.
Adopt current mode switch power supply overpower-protection circuit of the present invention, the duty cycle of switching of power switch pipe and current sampling signal are monitored simultaneously, judges whether Switching Power Supply enters over-power condition, and close power switch pipe in time.Effectively prevent due to current sampling resistor abnormal state cause circuit to enter over-power condition after the generation of circuit deterioration extent that may occur.
Power switch pipe under normal condition is run continuously with big space rate, such as output voltage is on the low side or the non-feedback in soft start stage, the present invention has done shieldingization process, and the time delay when judging overpower also avoids the chip closedown that false triggering over-power condition causes to a certain extent.
Previously described is each preferred embodiment of the present invention, preferred implementation in each preferred embodiment is if not obviously contradictory or premised on a certain preferred implementation, each preferred implementation can stack combinations use arbitrarily, design parameter in described embodiment and embodiment is only the invention proof procedure in order to clear statement inventor, and be not used to limit scope of patent protection of the present invention, scope of patent protection of the present invention is still as the criterion with its claims, the equivalent structure change that every utilization specification of the present invention and accompanying drawing content are done, in like manner all should be included in protection scope of the present invention.
Claims (7)
1.
current mode switch power supply overpower-protection circuit, comprises power switch pipe current detecting end, load
State-detection end and pulse width modulating signal end, is characterized in that, also comprise input over-power detection circuit (201), input normal power testing circuit (202), counting lock-in circuit, described input over-power detection circuit (201) comprising:
First decision circuitry, its input is connected with power switch pipe current detecting end, judge that whether power switch pipe current detecting terminal voltage is lower than a preset value V1, and whether be greater than one lower than duration of this V1 and preset duration T1, and export the first judgement signal;
To power switch pipe, maximum duty cycle testing circuit, occurs that maximum duty cycle detects and exports maximum duty cycle detection signal;
With logical operation circuit, judge that signal and maximum duty cycle detection signal carry out and computing to first, export overpower detection signal;
Described input normal power testing circuit comprises:
Second decision circuitry, its input is connected with load condition test side with power switch pipe current detecting end,
The voltage relationship of both judgements, and export the second judgement signal as input normal power detection signal;
Described counting lock-in circuit comprises:
Counter (203), the input end of clock of counter is connected with pulse width modulating signal end, and clear terminal is connected with input normal power detection signal, and signal input part is connected with overpower detection signal, and described counter exports overpower confirmation signal;
State lock-in circuit (204), its input is connected with overpower confirmation signal, output exports overpower locking signal, be connected with power switch pipe ON-OFF control circuit, when overpower locking signal being detected, making power switch pipe ON-OFF control circuit control power switch pipe and being locked in closed condition.
2. current mode switch power supply overpower-protection circuit as claimed in claim 1, is characterized in that,
Described first decision circuitry comprises a comparator and a delay circuit, and the DC level that the input of described comparator is V1 with power switch pipe current detecting end and magnitude of voltage is respectively connected, and the output of described comparator is connected with delay circuit input; Described delay circuit detects that comparator level changes, and exports first and judge signal after postponing to preset duration T1.
3. current mode switch power supply overpower-protection circuit as claimed in claim 1, it is characterized in that, described input normal power testing circuit also comprise the 3rd decision circuitry and or logical operation circuit, described 3rd decision circuitry judges soft start voltage SS and the power switch pipe current detecting terminal voltage of current mode switch power supply, and exports the 3rd and judge signal;
Described second judges that signal and the 3rd judges that signal all inputs or logical operation circuit carries out or computing, or the output signal of logical operation circuit is as input normal power detection signal.
4. current mode switch power supply overpower-protection circuit as claimed in claim 3, it is characterized in that, described 3rd decision circuitry is comparator, and the input of comparator is connected with soft start voltage SS and power switch pipe current detecting terminal voltage respectively.
5. current mode switch power supply overpower-protection circuit as claimed in claim 1, it is characterized in that, described second decision circuitry is comparator, and the input of comparator is connected with load condition test side and power switch pipe current detecting terminal voltage respectively.
6. current mode switch power supply overpower-protection circuit as described in claim 2 or 4 or 5 any one; it is characterized in that; described comparator also comprises input voltage regulation device, and input voltage regulation is normally made comparisons in the scope of result can make comparator by described input voltage regulation device.
7. current mode switch power supply overpower-protection circuit as claimed in claim 1, is characterized in that, the overpower locking signal control switch power supply chip that described state lock-in circuit exports is closed and made it no longer work.
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| CN112953242B (en) * | 2021-03-25 | 2023-02-17 | 深圳南云微电子有限公司 | Instantaneous overpower control method and circuit |
| CN114123787B (en) * | 2021-11-09 | 2023-10-10 | 珠海格力电器股份有限公司 | Switching power supply circuit and switching power supply |
| CN117873260A (en) * | 2024-03-12 | 2024-04-12 | 武汉永力睿源科技有限公司 | DC synthesized power matching circuit and control method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR0162847B1 (en) * | 1996-03-08 | 1999-04-15 | 김광호 | Smps with the function to protect overcurrent and overvoltage |
| KR100265374B1 (en) * | 1996-08-14 | 2000-09-15 | 윤종용 | Overcurrent protect circuit |
| US7149098B1 (en) * | 2006-01-04 | 2006-12-12 | System General Corporation | Over-power protection apparatus with programmable over-current threshold |
| CN102354956B (en) * | 2011-09-02 | 2014-08-27 | 聚辰半导体(上海)有限公司 | Switch power controller and short-circuit protection method of current control end thereof |
| CN103208934B (en) * | 2012-01-11 | 2016-12-14 | 成都启臣微电子股份有限公司 | A kind of pulse width modulating switch power source controller and Switching Power Supply |
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Address after: 610000 innovation center, No. 4, West core road, hi tech West District, Sichuan, Chengdu C341-343 Patentee after: Chengdu Qi Chen electronic Limited by Share Ltd Address before: 610000 innovation center, No. 4, West core road, hi tech West District, Sichuan, Chengdu C341-343 Patentee before: Chengdu Chip-Rail Microelectronic Co., Ltd. |