CN108988297B - Hiccup time control circuit and switching power supply comprising same - Google Patents
Hiccup time control circuit and switching power supply comprising same Download PDFInfo
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- CN108988297B CN108988297B CN201810996448.1A CN201810996448A CN108988297B CN 108988297 B CN108988297 B CN 108988297B CN 201810996448 A CN201810996448 A CN 201810996448A CN 108988297 B CN108988297 B CN 108988297B
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- 208000031361 Hiccup Diseases 0.000 title claims abstract description 50
- 239000003990 capacitor Substances 0.000 claims description 94
- 239000003381 stabilizer Substances 0.000 claims description 54
- 238000007599 discharging Methods 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 abstract 2
- 230000007423 decrease Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 238000012938 design process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 230000002035 prolonged effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1203—Circuits independent of the type of conversion
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
The invention provides a hiccup time control circuit and a switching power supply comprising the same. When the output end of the switching power supply is over-current or short-circuited, the voltage of the input end of the compensation level rises, when the voltage rises to a first specific value, the voltage of the output end of the trigger circuit is changed from high voltage to low voltage rapidly, the voltage of the output end of the delay circuit is slowly reduced from initial high voltage, when the voltage of the output end of the delay circuit is reduced to a second specific value, the output end of the control circuit turns off the switching power supply through the control end, and the working time of the output over-current or short-circuit hiccup protection of the switching power supply can be regulated by regulating the parameters of the delay circuit.
Description
Technical field:
the invention relates to the field of power supply circuits, in particular to a hiccup time control circuit and a switching power supply comprising the same.
The background technology is as follows:
the switching power supply is taken as a core component of the modern electric energy conversion technology and is widely applied to various power utilization occasions, whether the switching power supply can safely and stably operate is directly related to circuit safety, equipment safety and even personal safety, and therefore, a protection circuit is usually added in the design of the switching power supply so as to ensure the safe and stable operation of the power supply.
In the use process of the switching power supply, when the output power exceeds the rated power, the reliability of each device in the switching power supply cannot be guaranteed, so that output overcurrent protection and output short-circuit protection circuits are added to the switching power supply in the design process, and the hiccup type overcurrent protection is widely applied due to the advantages of high reliability, low power consumption, no influence on starting performance and the like. The operating principle of the hiccup type protection circuit is that when the switching power supply is started, the switching power supply starts to output power, when the power supply continuously works for a period of time, if the output voltage cannot reach the rated output voltage, or the output current continuously exceeds the maximum output current for a period of time, the protection circuit judges that the power supply works in an output overcurrent or output short-circuit state, at the moment, the protection circuit turns off the switching power supply, the power supply does not have power output any more, the protection circuit starts to count time, when the protection circuit counts for a certain time, the protection circuit exits from the protection state, namely, the switching power supply is restarted, the next starting process is started, and the hiccup protection period is completed.
In order to achieve miniaturization of the switching power supply, an overcurrent hiccup protection function is integrated in many switching power supply control ICs, but the overcurrent hiccup protection time integrated in many ICs cannot be accurately adjusted, particularly when the switching power supply is in an overcurrent or short-circuit hiccup state, the internal power device of the switching power supply is often damaged due to the fact that the internal power device cannot bear the excessively long working time in the hiccup state, and the reliability of the switching power supply is seriously affected.
Disclosure of Invention
In view of the above, the present invention overcomes the above disadvantages, and provides a hiccup time control circuit that can implement the adjustment of the operating time of the output overcurrent or short-circuit hiccup protection of the switching power supply by adjusting the parameters of the delay circuit.
Accordingly, another object of the present invention is to provide a switching power supply that can achieve adjustment of the operating time of the switching power supply for output overcurrent or short-circuit hiccup protection by adjusting the delay circuit parameters.
In order to achieve the above object, the present invention provides a hiccup time control circuit, which includes a trigger circuit, a delay circuit, a control circuit, four connection terminals, a compensation level input terminal, a control terminal, a power supply terminal, and a ground terminal.
The input end of the trigger circuit is connected with the compensation level input end, the output end of the trigger circuit is connected with the input end of the delay circuit, the output end of the delay circuit is connected with the input end of the control circuit, and the output end of the control circuit is connected with the control end;
when the voltage of the input end of the trigger circuit is larger than a first specific value, the voltage of the output end of the trigger circuit is changed from high voltage to low voltage rapidly, and conversely, when the voltage of the input end of the trigger circuit is smaller than the first specific value, the voltage of the output end of the trigger circuit is changed from low voltage to high voltage rapidly;
when the voltage of the output end of the trigger circuit is changed from high voltage to low voltage rapidly, the voltage of the output end of the delay circuit is slowly reduced from initial high voltage to a second specific value, and when the voltage of the output end of the delay circuit is reduced to the second specific value, the voltage of the output end of the delay circuit is slowly increased until the initial high voltage is recovered;
the output end of the control circuit is a control end, when the voltage of the output end of the trigger circuit is lower than a third specific value, the output end is low level, and when the voltage of the output end of the trigger circuit is higher than a fourth specific value, the output end is in a high resistance state.
In short, the hiccup time control circuit provided by the invention comprises a trigger circuit, a delay circuit and a control circuit, wherein the input end of the trigger circuit is used as the input end of a hiccup protection circuit and is used for being connected with the compensation level input end of a control chip; the trigger circuit comprises a first voltage stabilizer; the control circuit comprises a first operational amplifier; the delay circuit comprises a second capacitor connected to the non-inverting input end of the first operational amplifier and a first capacitor connected in series with the second capacitor; when the voltage of the input end of the trigger circuit is larger than the reference voltage set by the first voltage stabilizer, the trigger circuit triggers the delay circuit, so that the voltage of the output end of the delay circuit slowly drops through discharging of the second capacitor to the first capacitor, and when the voltage of the end of the second capacitor is lower than the voltage of the inverted input end of the first operational amplifier, the control circuit outputs a protection control signal to control the switching power supply to stop working; then the power supply end charges the second capacitor, and when the end voltage of the second capacitor rises to be higher than the voltage of the inverting input end of the first operational amplifier, the control circuit withdraws the protection control signal to start restarting the switching power supply; when the voltage of the input end of the trigger circuit is smaller than the reference voltage set by the first voltage stabilizer, the switching power supply exits the protection state.
Preferably, the trigger circuit includes a first resistor, a second resistor, a third resistor, and a first voltage stabilizer, where the first voltage stabilizer includes a reference terminal, an anode, and a cathode, and the connection relationship is: one end of the first resistor is an input end of the trigger circuit, the other end of the first resistor is connected with a reference end of the first voltage stabilizer, the reference end of the first voltage stabilizer is grounded through the second resistor, the power supply end is connected with a cathode of the first voltage stabilizer through the third resistor, an anode of the first voltage stabilizer is grounded, and the cathode of the first voltage stabilizer is an output end of the trigger circuit.
Preferably, the trigger circuit further comprises a third capacitor connected in parallel with the second resistor.
Preferably, the delay circuit includes a fourth resistor, a fifth resistor, a first capacitor, a second capacitor, and a second diode, and the connection relationship is: the power supply end is connected with the anode of the second diode through the fourth resistor, the cathode of the second diode is connected with the power supply end, one end of the fifth resistor is connected with the anode of the second diode, the other end of the fifth resistor is connected with one end of the second capacitor, the other end of the second capacitor is grounded, the anode of the second diode is connected with one end of the first capacitor, the other end of the first capacitor is the input end of the delay circuit, and the connection point of the fifth resistor and the second capacitor is the output end of the delay circuit.
Preferably, the control circuit includes a sixth resistor, a seventh resistor, a first diode, and a first operational amplifier, and the connection relationship is: the power supply end of the first operational amplifier is connected with the power supply end, the power supply end of the first operational amplifier is grounded, the power supply end is connected with the inverting input end of the first operational amplifier through a sixth resistor, the non-inverting input end of the first operational amplifier is grounded through a seventh resistor, the output end of the first operational amplifier is connected with the cathode of the first diode, the anode of the first diode is the output end of the control circuit, and the non-inverting input end of the first operational amplifier is the input end of the control circuit.
Preferably, the control circuit includes a sixth resistor, a seventh resistor, an eighth resistor, a first diode, and a first operational amplifier, and the connection relationship is: the power supply end of the first operational amplifier is connected with the power supply end, the power supply end of the first operational amplifier is grounded, the power supply end is connected with the inverting input end of the first operational amplifier through a sixth resistor, the non-inverting input end of the first operational amplifier is grounded through a seventh resistor, the non-inverting input end of the first operational amplifier is connected with the output end of the first operational amplifier through an eighth resistor, the output end of the first operational amplifier is connected with the cathode of the first diode, the anode of the first diode is the output end of the control circuit, and the non-inverting input end of the first operational amplifier is the input end of the control circuit.
The invention also provides a switching power supply applying the technical scheme, when the current of the output end of the switching power supply is increased abnormally or the output end of the switching power supply is short-circuited, the level of the compensation level input end is increased, and when the output current of the switching power supply is reduced, the level of the compensation level input end is reduced; when the output end of the control circuit is in a low level, the switching power supply stops working, and when the output end of the control circuit is in a high resistance state, the switching power supply resumes working.
The invention further provides a switching power supply, which comprises the hiccup time control circuit, wherein when the output end of the switching power supply is in overcurrent or short circuit, the level of the input end of the compensation level is increased to be larger than the protection trigger reference voltage, the trigger circuit triggers the delay circuit, and when the second capacitor of the delay circuit is discharged to be lower than the voltage of the inverted input end of the first operational amplifier, the control circuit outputs a low-level protection control signal to control the switching power supply to stop working; then the power supply end charges the second capacitor, when the end voltage of the second capacitor rises to be higher than the voltage of the reverse phase input end of the first operational amplifier, the control circuit withdraws the protection control signal to restart the switching power supply, so that a complete hiccup protection period is formed, and hiccup protection of the switching power supply is realized through repeated circulation; when the switching power supply exits from overcurrent or short circuit, the level of the input end of the compensation level is reduced to be smaller than the protection trigger reference voltage, the output end of the control circuit is in a high-resistance state, the switching power supply exits from a protection state, and normal operation is automatically restored; wherein the protection trigger reference voltage is set by an internal reference voltage of the first voltage regulator of the trigger circuit.
The working principle of the invention is described as follows:
a hiccup time control circuit of a switching power supply mainly comprises three circuits and four terminals: the circuit comprises a trigger circuit, a delay circuit, a control circuit, a compensation level input end, a control end, a power supply end and a grounding end.
In a conventional switching power supply, there is a compensation level input terminal Comp (or FB) associated with a voltage loop, which is characterized in that: in a steady state, the level of the compensation level input terminal is a steady direct current voltage, when the output current of the power supply increases, the level of the compensation level input terminal Comp (or FB) correspondingly increases, and conversely, when the output current decreases, the level of the compensation level input terminal Comp (or FB) correspondingly decreases.
When the voltage of the reference end of the first voltage stabilizer is increased to be higher than the internal reference voltage, the current flowing into the first three-section voltage stabilizer is rapidly increased, the current flowing through the third resistor is rapidly increased, the voltages at two ends of the third resistor are rapidly increased, the voltage of the cathode of the first voltage stabilizer is rapidly reduced under the voltage division effect of the third resistor, the voltage at two ends of the first capacitor cannot be suddenly changed, the anode voltage of the second diode is also rapidly changed into the low level when the voltage of the cathode of the first voltage stabilizer is changed into the low level from the high level, the current flowing from the power supply end through the fourth resistor and the current flowing into the second capacitor through the fifth resistor start to charge the first capacitor, and the anode voltage of the second diode is slowly increased; when the voltage of the anode of the second diode is changed from high level to low level, the voltage of the two ends of the second capacitor is higher than the voltage of the anode of the second diode, the charge on the second capacitor charges the first capacitor through the fifth resistor, the voltage of the two ends of the second capacitor starts to drop, when the voltage of the two ends of the second capacitor drops to be lower than the voltage of the inverting input end of the first operational amplifier, the voltage of the output end of the first operational amplifier is changed to low level, the voltage of the control end is correspondingly changed from high resistance state to low level, and the switching power supply stops working; when the voltage on the second capacitor is reduced to be lower than the anode voltage of the second diode, the current of the power supply end flows into the second capacitor through the fourth resistor and the fifth resistor, the voltage at two ends of the second capacitor starts to be slowly increased, and finally the voltage is increased to be the same as the voltage of the power supply end. The falling slope of the voltage of the second capacitor can be adjusted by adjusting the parameters of the first capacitor, the second capacitor, the fourth resistor and the fifth resistor, and the delay time from the triggering of the overcurrent protection by the trigger circuit to the reduction of the output level of the control end can be adjusted; when the voltage of the two ends of the second capacitor rises to be higher than the voltage of the inverting input end of the first operational amplifier, the control end is changed into a high-resistance state again, and the switching power supply begins to work again.
When the output end of the switching power supply exits from an overcurrent or short circuit state, the voltage of the input end of the compensation level is reduced, the voltage of the reference end of the first voltage stabilizer is correspondingly reduced under the voltage division effect of the first resistor and the second resistor, when the voltage of the reference end of the first voltage stabilizer is reduced to be lower than the internal reference voltage of the first voltage stabilizer, the current flowing into the first voltage stabilizer is rapidly reduced, the current flowing through the third resistor begins to be reduced, the charge on the first capacitor is consumed through the second diode and the third resistor, the voltage at the two ends of the first capacitor is finally changed to zero again, and the whole hiccup time control circuit completes one-time overcurrent hiccup protection control.
The invention has the beneficial effects that:
(1) The circuit adopts a voltage stabilizer to trigger overcurrent or short-circuit protection, and the control precision of an overcurrent point is high.
(2) The circuit can realize the accurate control of the overcharging time by adopting a common operational amplifier and a voltage stabilizer, and has simple circuit and low cost.
Drawings
FIG. 1 is a schematic block diagram of a hiccup time control circuit of the present invention;
FIG. 2 is a schematic diagram of a hiccup time control circuit according to a first embodiment of the present invention;
fig. 3 is a schematic diagram of a hiccup time control circuit according to a second embodiment of the present invention.
Detailed Description
The invention provides a hiccup time control circuit and a technical scheme of a switching power supply applying the same, which are used for realizing the hiccup protection control of the overcurrent or short circuit of the switching power supply. In the switching power supply, the compensation level input terminal Comp and/or the voltage feedback terminal FB related to the voltage loop are/is present in the conventional control chip, and thus the compensation level input terminal Comp and/or the voltage feedback terminal FB includes current information flowing through the power device, and can be used to reflect whether the output of the switching power supply has an overcurrent or a short circuit. The detailed description of the specific embodiments will now be made by taking the compensation level Comp of the control chip as an example.
In order that the invention may be more readily understood, a more particular description thereof will be rendered by reference to specific embodiments that are illustrated in the appended drawings. It should be noted that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
First embodiment
Referring to fig. 2, a hiccup time control circuit of a switching power supply includes a trigger circuit, a delay circuit, a control circuit, a compensation level input terminal Comp, a control terminal, a power supply terminal Vcc and a ground terminal.
The trigger circuit comprises a first resistor R1, a second resistor R2, a third resistor R3 and a first voltage stabilizer, wherein the first voltage stabilizer comprises a reference end, an anode and a cathode, and the connection relation is as follows: one end of the first resistor R1 is an input end of the trigger circuit, the other end of the first resistor R1 is connected with a reference end of the first voltage stabilizer, and the reference end of the first voltage stabilizer is also connected with a grounding end (the grounding end is connected with the grounding end of the control chip, and is called grounding for short hereinafter) through the second resistor R2; the power supply end Vcc is connected with the cathode of the first voltage stabilizer through a third resistor R3, and the anode of the first voltage stabilizer is grounded; the cathode of the first voltage stabilizer is the output end of the trigger circuit. The first voltage regulator is preferably a three-terminal voltage regulator, and in this embodiment, the voltage regulator TL431 is preferably exemplified.
The delay circuit comprises a fourth resistor R4, a fifth resistor R5, a first capacitor C1, a second capacitor C2 and a second diode D2, and the connection relation is as follows: the power supply end Vcc is connected with the anode of a second diode D2 through a fourth resistor R4, the cathode of the second diode D2 is connected with the power supply end Vcc, one end of a fifth resistor R5 is connected with the anode of the second diode D2, the other end of the fifth resistor R5 is connected with one end of a second capacitor C2, and the other end of the second capacitor C2 is grounded; the anode of the second diode D2 is connected with one end of the first capacitor C1, and the other end of the first capacitor C1 is the input end of the delay circuit; the connection point of the fifth resistor R5 and the second capacitor C2 is an output end of the delay circuit.
The control circuit comprises a sixth resistor R6, a seventh resistor R7, a first diode D1 and a first operational amplifier AR1, and the connection relation is as follows: the power supply end of the first operational amplifier AR1 is connected with the power supply end Vcc, the power supply end of the first operational amplifier AR1 is grounded, the power supply end is connected with the inverting input end of the first operational amplifier AR1 through a sixth resistor R6, the inverting input end of the first operational amplifier AR1 is also grounded through a seventh resistor R7, the output end of the first operational amplifier AR1 is connected with the cathode of the first diode D1, the anode of the first diode D1 is the output end of the control circuit, and the non-inverting input end of the first operational amplifier AR1 is the input end of the control circuit.
The input end of the trigger circuit is connected with the compensation level input end Comp, the output end of the trigger circuit is connected with the input end of the delay circuit, the output end of the delay circuit is connected with the input end of the control circuit, and the output end of the control circuit is connected with the control end. The control terminal can be defined as an enabling pin, an under-voltage protection pin or a current compensation control pin due to different pin function definitions of different chips, and the like, so that the pin can stop outputting the switch power supply product after the level of the pin is pulled down.
A switching power supply applying the technical scheme,
the level of the compensation level input terminal increases when the current of the output terminal of the switching power supply increases or the output terminal is short-circuited, and the level of the compensation level input terminal decreases when the output current of the switching power supply decreases.
When the output end of the control circuit is in a low level, the switching power supply stops working, and when the output end of the control circuit is in a high resistance state, the switching power supply resumes working.
The working principle is as follows:
in a stable operating state, the Comp level of the Comp input end of the switching power supply is a stable DC voltage, when the output current of the power supply increases, the Comp level of the Comp input end increases, and conversely, when the output current decreases, the Comp level of the Comp input end decreases.
When the voltage of the reference end of the first voltage stabilizer TL431 rises to be higher than the internal reference voltage (usually 2.5V), the current flowing into the first voltage stabilizer TL431 increases rapidly, the current flowing through the third resistor R3 increases rapidly, the voltage at two ends of the third resistor R3 increases rapidly, the voltage at the cathode of the first voltage stabilizer TL431 decreases rapidly due to the series connection of the third resistor R3 and the cathode of the first voltage stabilizer TL431 under the voltage division effect, the voltage at two ends of the capacitor C1 cannot be suddenly changed, the anode voltage of the second diode D2 also becomes rapidly low when the voltage at the cathode of the first voltage stabilizer TL431 changes from high level to low level, the current flowing from the power supply end Vcc through the fourth resistor R4 and the current flowing into the anode of the second capacitor C2 through the fifth resistor R5 start to charge slowly as the first capacitor C1, and the anode voltage of the second diode D2 increases slowly. When the anode voltage of the second diode D2 is changed from high level to low level, since the voltage at both ends of the second capacitor C2 is higher than the anode voltage of the second diode D2 at this time, the charge on the second capacitor C2 charges the first capacitor C1 through the fifth resistor R5, the voltage at both ends of the second capacitor C2 starts to drop, when the voltage at both ends of the second capacitor C2 drops below the voltage of the inverting input end of the first operational amplifier AR1, the voltage at the output end of the first operational amplifier AR1 becomes low level, the diode D1 is turned on, the control end is pulled down to ground, and the switching power supply stops working; when the voltage on the second capacitor C2 drops to be lower than the anode voltage of the second diode D2, the Vcc current of the power supply end flows into the second capacitor through the fourth resistor R4 and the fifth resistor R5, the voltage at two ends of the second capacitor C2 starts to rise slowly, and finally the voltage is raised to be the same as the Vcc voltage of the power supply end; when the voltage at two ends of the second capacitor C2 rises to be higher than the voltage at the inverting input end of the first operational amplifier AR1, the output of the first operational amplifier AR1 is at a high level, the diode D1 is turned off reversely, and the control end is turned into a high resistance state again, so that the switching power supply is turned on again. The protection duration of the hiccup time control circuit, namely the period duration of the hiccup, can adjust the falling slope of the voltage of the second capacitor C2 by adjusting the parameters of the first capacitor C1, the second capacitor C2, the fourth resistor R4 and the fifth resistor R5, and can adjust the delay time from the triggering circuit to trigger the overcurrent protection to the reduction of the output level of the control end. The reference voltage of the circuit is formed by inherent characteristic parameters of circuit devices, and whether the output of the switching power supply is over-current or short-circuited can be accurately judged without external reference voltage.
When the output end of the switching power supply exits from an overcurrent or short circuit state, the voltage of the Comp input end of the compensation level is reduced, the voltage of the reference end of the first voltage stabilizer TL431 is correspondingly reduced under the voltage division effect of the first resistor R1 and the second resistor R2, when the voltage of the reference end of the first voltage stabilizer TL431 is reduced to be lower than the internal reference voltage, the current flowing into the first voltage stabilizer TL431 is rapidly reduced, the current flowing through the third resistor R3 begins to be reduced, the charge on the first capacitor C1 is consumed through the second diode D2 and the third resistor R3, the voltage at the two ends of the first capacitor C1 is finally changed to zero again, the switching power supply automatically returns to a normal working state, and the whole hiccup time control circuit completes the hiccup type protection control of one-time overcurrent.
The hiccup time control circuit provided by the invention realizes independent debugging of the hiccup interval time and the working time under the power supply output overcurrent or short circuit state, and can prevent the problem of short circuit damage of the switching power supply by adjusting the working time and the interval time during hiccup. The circuit can accurately judge whether the power supply output is over-current or short-circuited without external reference voltage. And the circuit adopts a common operational amplifier and a voltage stabilizer to realize the modulation of the overcurrent hiccup time, and the circuit is simple and has low cost.
Second embodiment
Fig. 3 shows a schematic diagram of a second embodiment, whose basic working principle is the same as that of the first embodiment, and the main difference is that the trigger circuit adds a third capacitor C3, the third capacitor C3 is connected in parallel with the second resistor R2, the control circuit adds an eighth resistor R8, one end of the eighth resistor R8 is connected to the non-inverting input end of the first operational amplifier AR1, and the other end of the resistor R8 is connected to the output end of the operational amplifier AR 1.
The working principle is different from the first embodiment in that: when the switching power supply does not enter an overcurrent or short-circuit state, the output end of the first operational amplifier AR1 is at a high level, when the switching power supply enters the overcurrent or short-circuit state, the voltage at two ends of the capacitor C2 starts to drop slowly from the high voltage, when the voltage at two ends of the capacitor C2 does not drop to the voltage of the inverted input end of the first operational amplifier AR1, the output end of the operational amplifier AR1 is still at the high level, the capacitor C2 is charged by current flowing through the resistor R8, the dropping speed of the voltage at two ends of the capacitor C2 is reduced, and therefore the starting working time of the power supply in the overcurrent hiccup protection state of the switching power supply is prolonged, when the voltage at two ends of the capacitor C2 drops to be lower than the voltage of the inverted input end of the first operational amplifier AR1, the output end of the operational amplifier AR1 is at a low level, and charges on the capacitor C2 flow into the output end of the operational amplifier AR1 through the resistor R8, so that the rising speed of the voltage at two ends of the capacitor C2 is slowed down, and the hiccup time interval of the power supply in the overcurrent hiccup protection state of the switching power supply is realized.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that the above-mentioned preferred embodiment should not be construed as limiting the invention, and that modifications and alterations can be made by those skilled in the art without departing from the spirit and scope of the invention, which is also regarded as the protection scope of the invention, which is defined by the claims without further description of the examples.
Claims (7)
1. A hiccup time control circuit, characterized by: comprises a trigger circuit, a delay circuit and a control circuit,
the input end of the trigger circuit is used as the input end of the hiccup time control circuit and is used for being connected with the compensation level input end of the control chip, the output end of the trigger circuit is connected with the input end of the delay circuit, the output end of the delay circuit is connected with the input end of the control circuit, and the output end of the control circuit is used as the output end of the hiccup time control circuit and is used for being connected with the control end of the control chip; the trigger circuit comprises a first voltage stabilizer, a first resistor, a second resistor and a third resistor, wherein the first voltage stabilizer comprises a reference end, an anode and a cathode, one end of the first resistor is an input end of the trigger circuit, the other end of the first resistor is connected with the reference end of the first voltage stabilizer, the reference end of the first voltage stabilizer is grounded through the second resistor, the power supply end is connected with the cathode of the first voltage stabilizer through the third resistor, the cathode of the first voltage stabilizer is used as an output end of the trigger circuit, and the anode of the first voltage stabilizer is grounded; the control circuit comprises a first operational amplifier, a sixth resistor, a seventh resistor and a first diode, wherein the power end of the first operational amplifier is connected with the power supply end, the power ground of the first operational amplifier is grounded, the power supply end is also connected with the inverting input end of the first operational amplifier through the sixth resistor, the inverting input end of the first operational amplifier is also grounded through the seventh resistor, the non-inverting input end of the first operational amplifier is the input end of the control circuit, the output end of the first operational amplifier is connected with the cathode of the first diode, and the anode of the first diode is the output end of the control circuit; the delay circuit comprises a first capacitor, a second capacitor, a fourth resistor, a fifth resistor and a second diode, wherein the power supply end is connected with the anode of the second diode through the fourth resistor, the cathode of the second diode is connected with the power supply end, one end of the fifth resistor is connected with the anode of the second diode, the other end of the fifth resistor is connected with one end of the second capacitor, the other end of the second capacitor is grounded, the anode of the second diode is connected with one end of the first capacitor, the other end of the first capacitor is the input end of the delay circuit, and the connection point of the fifth resistor and the second capacitor is the output end of the delay circuit;
when the voltage of the input end of the trigger circuit is larger than the reference voltage set by the first voltage stabilizer, the trigger circuit triggers the delay circuit, so that the voltage of the output end of the delay circuit slowly drops through discharging of the second capacitor to the first capacitor, and when the voltage of the end of the second capacitor is lower than the voltage of the inverted input end of the first operational amplifier, the control circuit outputs a protection control signal to control the switching power supply to stop working; then the power supply end charges the second capacitor, and when the end voltage of the second capacitor rises to be higher than the voltage of the inverting input end of the first operational amplifier, the control circuit withdraws the protection control signal to start restarting the switching power supply;
when the voltage of the input end of the trigger circuit is smaller than the reference voltage set by the first voltage stabilizer, the switching power supply exits the protection state.
2. The hiccup time control circuit of claim 1, wherein: the trigger circuit further comprises a third capacitor connected in parallel with the second resistor.
3. The hiccup time control circuit of claim 1, wherein: the control circuit further comprises an eighth resistor, one end of the eighth resistor is connected with the non-inverting input end of the first operational amplifier, and the other end of the eighth resistor is connected with the output end of the first operational amplifier.
4. A hiccup time control circuit comprises a trigger circuit, a delay circuit and a control circuit,
the trigger circuit comprises a first resistor, a second resistor, a third resistor and a first voltage stabilizer, wherein the first voltage stabilizer comprises a reference end, an anode and a cathode, and the connection relation is as follows: one end of the first resistor is an input end of the trigger circuit, the other end of the first resistor is connected with a reference end of the first voltage stabilizer, the reference end of the first voltage stabilizer is grounded through the second resistor, the power supply end is connected with a cathode of the first voltage stabilizer through the third resistor, the cathode of the first voltage stabilizer is used as an output end of the trigger circuit, and an anode of the first voltage stabilizer is grounded;
the delay circuit comprises a fourth resistor, a fifth resistor, a first capacitor, a second capacitor and a second diode, and the connection relation of the delay circuit is as follows: the power supply end is connected with the anode of the second diode through a fourth resistor, the cathode of the second diode is connected with the power supply end, one end of a fifth resistor is connected with the anode of the second diode, the other end of the fifth resistor is connected with one end of a second capacitor, the other end of the second capacitor is grounded, the anode of the second diode is connected with one end of a first capacitor, the other end of the first capacitor is the input end of the delay circuit, and the connection point of the fifth resistor and the second capacitor is the output end of the delay circuit;
the control circuit comprises a sixth resistor, a seventh resistor, a first diode and a first operational amplifier, and the connection relation is as follows: the power supply end of the first operational amplifier is connected with the power supply end, the power supply ground end of the first operational amplifier is connected with the inverting input end of the first operational amplifier through a sixth resistor, the inverting input end of the first operational amplifier is also connected with the ground through a seventh resistor, the non-inverting input end of the first operational amplifier is an input end of the control circuit, the output end of the first operational amplifier is connected with the cathode of the first diode, and the anode of the first diode is an output end of the control circuit.
5. The hiccup time control circuit of claim 4, wherein: the trigger circuit further comprises a third capacitor, and the third capacitor is connected with the second resistor in parallel; the control circuit further comprises an eighth resistor, one end of the eighth resistor is connected with the non-inverting input end of the first operational amplifier, and the other end of the eighth resistor is connected with the output end of the first operational amplifier.
6. The hiccup time control circuit of claim 4 or 5, wherein: the first voltage stabilizer is a three-terminal voltage stabilizer.
7. A switching power supply comprising the hiccup time control circuit of any one of claims 1 to 5, characterized in that:
when the output end of the switching power supply generates overcurrent or short circuit, the level of the input end of the compensation level rises to be larger than the protection trigger reference voltage, the trigger circuit triggers the delay circuit, and when the second capacitor of the delay circuit discharges to be lower than the voltage of the inverted input end of the first operational amplifier, the control circuit outputs a low-level protection control signal to control the switching power supply to stop working; then the power supply end charges the second capacitor, and when the end voltage of the second capacitor rises to be higher than the voltage of the inverting input end of the first operational amplifier, the control circuit withdraws the protection control signal to start restarting the switching power supply;
when the switching power supply exits from overcurrent or short circuit, the level of the input end of the compensation level is reduced to be smaller than the protection trigger reference voltage, the output end of the control circuit is in a high-resistance state, the switching power supply exits from a protection state, and normal operation is automatically restored;
wherein the protection trigger reference voltage is set by an internal reference voltage of the first voltage regulator of the trigger circuit.
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| CN201810996448.1A CN108988297B (en) | 2018-08-29 | 2018-08-29 | Hiccup time control circuit and switching power supply comprising same |
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| CN201810996448.1A CN108988297B (en) | 2018-08-29 | 2018-08-29 | Hiccup time control circuit and switching power supply comprising same |
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| CN108988297B true CN108988297B (en) | 2024-02-13 |
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| CN112290512B (en) * | 2020-10-23 | 2023-03-14 | 广州金升阳科技有限公司 | Switch power supply overcurrent protection circuit capable of preventing false triggering |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2904418Y (en) * | 2006-01-13 | 2007-05-23 | 北京动力源科技股份有限公司 | Primary current limiting circuit for switch power |
| CN102193509A (en) * | 2010-03-01 | 2011-09-21 | 株式会社村田制作所 | Switching control circuit and switching power supply device |
| CN102280861A (en) * | 2011-08-01 | 2011-12-14 | 广州金升阳科技有限公司 | Output short-circuit protection circuit of switching power supply |
| CN108258656A (en) * | 2018-02-28 | 2018-07-06 | 厦门讯亨电子科技有限公司 | Switching Power Supply overloads delay protection circuit |
| CN208890353U (en) * | 2018-08-29 | 2019-05-21 | 广州金升阳科技有限公司 | Hiccup time control circuit and the Switching Power Supply comprising the circuit |
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2018
- 2018-08-29 CN CN201810996448.1A patent/CN108988297B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2904418Y (en) * | 2006-01-13 | 2007-05-23 | 北京动力源科技股份有限公司 | Primary current limiting circuit for switch power |
| CN102193509A (en) * | 2010-03-01 | 2011-09-21 | 株式会社村田制作所 | Switching control circuit and switching power supply device |
| CN102280861A (en) * | 2011-08-01 | 2011-12-14 | 广州金升阳科技有限公司 | Output short-circuit protection circuit of switching power supply |
| CN108258656A (en) * | 2018-02-28 | 2018-07-06 | 厦门讯亨电子科技有限公司 | Switching Power Supply overloads delay protection circuit |
| CN208890353U (en) * | 2018-08-29 | 2019-05-21 | 广州金升阳科技有限公司 | Hiccup time control circuit and the Switching Power Supply comprising the circuit |
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| CN108988297A (en) | 2018-12-11 |
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