CN217545563U - Output voltage-limiting overpower protection circuit of switching power supply - Google Patents
Output voltage-limiting overpower protection circuit of switching power supply Download PDFInfo
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- CN217545563U CN217545563U CN202123397022.0U CN202123397022U CN217545563U CN 217545563 U CN217545563 U CN 217545563U CN 202123397022 U CN202123397022 U CN 202123397022U CN 217545563 U CN217545563 U CN 217545563U
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Abstract
The utility model discloses a switching power supply output voltage limiting overpower protection circuit, zener diode DZ1 is anodal to be connected with resistance R1 one end in this circuit, resistance R1 one end and electric capacity C1's one end, resistance R2 one end, triode Q1 base is connected, zener diode DZ1 negative pole and PWM chip U1's feedback pin FB, opto-coupler PC1 collecting electrode is connected, the electric capacity C1 other end and opto-coupler PC1 projecting pole, the resistance R2 other end, triode Q1 projecting pole, switching power supply's input negative pole end Vin-is connected, triode Q1 collecting electrode and PWM chip U1 overtemperature protection pin RT are connected, opto-coupler PC1 input connects in parallel on voltage stabilizing circuit WY1, switching power supply's the positive negative pole of output is connected respectively at voltage stabilizing circuit WY 1's both ends. The utility model discloses can act rapidly when output voltage overpower and let output voltage become the zero value in the twinkling of an eye, solve the problem that output voltage reduces gradually.
Description
Technical Field
The utility model relates to a switching power supply technical field especially relates to a switching power supply output voltage limiting overpower protection circuit.
Background
Most have the needs of singlechip work in the supporting terminal that uses of switching power supply, the direct current voltage of singlechip work is most about 5V, these voltage for singlechip work have minimum and the highest value restriction, if switching power supply is too low for the direct current voltage of the singlechip power supply on the terminal, then the singlechip will work unstably and be chaotic more easily, however, when switching power supply for the load power supply and the condition of overpower appears, the condition that reduces gradually will appear in output voltage, this output voltage also is for the singlechip power supply simultaneously, will lead to the operating voltage of singlechip to hang down excessively, this problem is waited for solving urgently.
SUMMERY OF THE UTILITY MODEL
The utility model provides a switching power supply output voltage limiting overpower protection circuit solves the problem that above background art part mentioned.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
a kind of switching power supply exports the over-power protective circuit of voltage limiting, this circuit includes voltage regulation diode DZ1, resistance R2, electric capacity C1 and triode Q1; the positive electrode of the voltage stabilizing diode DZ1 is connected with one end of a resistor R1, the other end of the resistor R1 is connected with one end of a capacitor C1, one end of a resistor R2 and the base electrode of a triode Q1, the negative electrode of the voltage stabilizing diode DZ1 is connected with a feedback pin FB of a PWM (pulse width modulation) chip U1 and the collector electrode of an optocoupler PC1, the other end of the capacitor C1 is connected with the emitter electrode of the optocoupler PC1, the other end of the resistor R2, the emitter electrode of the triode Q1 and the input negative electrode Vin-of a switching power supply, the collector electrode of the triode Q1 is connected with the over-temperature protection pin RT of the PWM chip U1, the input end of the optocoupler PC1 is connected on a voltage stabilizing circuit WY1 in parallel, and the two ends of the voltage stabilizing circuit WY1 are respectively connected with the output positive electrode Vout + of the switching power supply and the output negative electrode Vout-.
Further, the triode Q1 is an NPN type triode.
The utility model provides a switching power supply output voltage limiting overpower protection circuit when overpower appears in switching power supply, the feedback loop that switching power supply output voltage and voltage stabilizing circuit WY1 formed risees the voltage of PWM chip U1's feedback pin FB, after the voltage on feedback pin FB surpassed zener diode DZ 1's setting value, zener diode DZ1 switches on, the voltage on feedback pin FB passes through zener diode DZ1, make triode Q1 switch on behind the resistance R1, PWM chip U1's overtemperature prote pin RT is connected to triode Q1's collecting electrode, the RT foot is a high level under the normal condition, will draw the level of overtemperature prote pin RT after triode Q1 switches on, then PWM chip U1 stop work, output voltage will become the zero value in the twinkling of an eye, thereby effectively avoided switching power supply output voltage under the condition of output overpower phenomenon that gradually reduces. The utility model discloses simple structure, the action is sensitive, and is with low costs, suitable popularization and application.
Drawings
FIG. 1 shows a switch according to an embodiment of the present invention the power output voltage limiting overpower protection circuit structure chart.
Detailed Description
In order to facilitate understanding of the present invention, the present invention will be described more fully hereinafter with reference to the accompanying drawings. The preferred embodiments of the present invention are illustrated in the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
As shown in fig. 1, fig. 1 is a structural diagram of an output voltage-limiting over-power protection circuit of a switching power supply according to an embodiment of the present invention.
The present embodiment provides a switching power supply output voltage limiting over-power protection circuit, which includes a zener diode DZ1, a resistor R2, a capacitor C1, and a transistor Q1. Specifically, in this embodiment, the positive electrode of the zener diode DZ1 is connected to one end of the resistor R1, the other end of the resistor R1 is connected to one end of the capacitor C1, one end of the resistor R2, and the base of the transistor Q1, the negative electrode of the zener diode DZ1 is connected to the feedback pin FB of the PWM chip U1 and the collector of the optocoupler PC1, the other end of the capacitor C1 is connected to the emitter of the optocoupler PC1, the other end of the resistor R2, the emitter of the transistor Q1, and the input negative electrode Vin-of the switching power supply, the collector of the transistor Q1 is connected to the over-temperature protection pin RT of the PWM chip U1, the input end of the optocoupler PC1 is connected in parallel to the voltage stabilizing circuit WY1, and the two ends of the voltage stabilizing circuit WY1 are respectively connected to the output positive electrode Vout + of the switching power supply and the output negative electrode Vout-. Specifically, in this embodiment, the transistor Q1 is an NPN transistor.
During operation, when the switching power supply normally works, a feedback loop formed by the voltage stabilizing circuit WY1 and the optocoupler PC1 stably works, the voltage of a feedback pin FB of the PWM chip U1 is low, and the voltage stabilizing diode DZ1 is not conducted under the condition that the voltage stabilizing feedback loop of the power supply output normally works by selecting a proper value. When the over-power of the switching power supply occurs, the voltage of a feedback pin FB of the PWM chip U1 is increased by a feedback loop formed by the output voltage of the switching power supply and the voltage stabilizing circuit WY1, when the voltage of the feedback pin FB exceeds a set value of the zener diode DZ1, the zener diode DZ1 is conducted, the voltage of the feedback pin FB passes through the zener diode DZ1 and the resistor R1 to conduct the transistor Q1, the collector of the transistor Q1 is connected to the over-temperature protection pin RT of the PWM chip U1, the RT pin is a high level under normal conditions, and when the transistor Q1 is conducted, the level of the over-temperature protection pin RT is lowered, the PWM chip U1 stops working, the output voltage instantly becomes a zero value, so that the phenomenon that the output voltage of the switching power supply is gradually lowered under the condition of outputting the over-power is effectively avoided, and the error triggering of the transistor Q1 can be effectively prevented by adding the capacitor C1 and the resistor R2 in the embodiment, so that the proposed over-power protection circuit for limiting output of the switching power supply is more stable and reliable. The utility model discloses simple structure, the action is sensitive, and is with low costs, suitable popularization and application.
It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, numerous obvious variations, adaptations and substitutions will occur to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.
Claims (2)
1. The over-power protection circuit for the output voltage limitation of the switching power supply is characterized by comprising a voltage stabilizing diode DZ1, a resistor R2, a capacitor C1 and a triode Q1; the positive electrode of the voltage stabilizing diode DZ1 is connected with one end of a resistor R1, the other end of the resistor R1 is connected with one end of a capacitor C1, one end of a resistor R2 and the base electrode of a triode Q1, the negative electrode of the voltage stabilizing diode DZ1 is connected with a feedback pin FB of a PWM chip U1 and the collector electrode of an optocoupler PC1, the other end of the capacitor C1 is connected with the emitter electrode of the optocoupler PC1, the other end of the resistor R2, the emitter electrode of the triode Q1 and the input negative electrode Vin-of a switching power supply, the collector electrode of the triode Q1 is connected with an over-temperature protection pin RT of the PWM chip U1, the input end of the optocoupler PC1 is connected in parallel with a voltage stabilizing circuit WY1, and the two ends of the voltage stabilizing circuit WY1 are respectively connected with the output positive electrode terminal Vout + of the switching power supply and the output negative electrode terminal Vout-.
2. The output voltage-limiting over-power protection circuit of the switching power supply according to claim 1, wherein the transistor Q1 is an NPN-type transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123397022.0U CN217545563U (en) | 2021-12-30 | 2021-12-30 | Output voltage-limiting overpower protection circuit of switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123397022.0U CN217545563U (en) | 2021-12-30 | 2021-12-30 | Output voltage-limiting overpower protection circuit of switching power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN217545563U true CN217545563U (en) | 2022-10-04 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202123397022.0U Active CN217545563U (en) | 2021-12-30 | 2021-12-30 | Output voltage-limiting overpower protection circuit of switching power supply |
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| Country | Link |
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| CN (1) | CN217545563U (en) |
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2021
- 2021-12-30 CN CN202123397022.0U patent/CN217545563U/en active Active
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