CN204068678U - A kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit - Google Patents

A kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit Download PDF

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Publication number
CN204068678U
CN204068678U CN201420327410.2U CN201420327410U CN204068678U CN 204068678 U CN204068678 U CN 204068678U CN 201420327410 U CN201420327410 U CN 201420327410U CN 204068678 U CN204068678 U CN 204068678U
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China
Prior art keywords
pin
resistance
chip
triode
diode
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Expired - Fee Related
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CN201420327410.2U
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Chinese (zh)
Inventor
卢建辉
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SHENZHEN COSTAR ELECTRONICS TECHNOLOGY Co Ltd
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SHENZHEN COSTAR ELECTRONICS TECHNOLOGY Co Ltd
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Priority to CN201420327410.2U priority Critical patent/CN204068678U/en
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Publication of CN204068678U publication Critical patent/CN204068678U/en
Expired - Fee Related legal-status Critical Current
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Abstract

The utility model discloses a kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit, it relates to a kind of protective circuit of switch power source.It comprises transformer, IC chip, triode and field effect transistor, the grid of field effect transistor connects 8 pin of the second resistance to IC chip, 2 pin of transformer feedback winding connect 7 pin of the first diode to IC chip, 7 pin of IC chip connect the positive pole of the first resistance to the second diode, the negative pole of the second diode connects the negative pole of voltage stabilizing didoe, the positive pole of voltage stabilizing didoe connects the base stage of triode, the 4th electric capacity and the 6th resistance is connected between the base stage of triode and emitter, thermistor is connected between the emitter of triode and collector electrode, the collector electrode of triode connects 5 pin of the 7th resistance to IC chip.The utility model cost is low, takes up room little, can not affect efficiency and electromagnetic interference, can obtain good output over-voltage protection and overheat protector effect, improve the safety and reliability of power supply.

Description

A kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit
Technical field
The utility model relates to a kind of protective circuit of switch power source, be specifically related to a kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit.
Background technology
Switching Power Supply is with small-sized, light weight and high efficiency feature are widely used in a lot of electronic equipment, it is the indispensable a kind of power mode of current electronics and information industry develop rapidly, existing Switching Power Supply output overvoltage protection circuit (as Fig. 1), normally detect output voltage, when the output voltage is too high, voltage stabilizing didoe conducting, optocoupler conducting, triode ON, thus protection voltage can be caused by IC chip to drag down, thus realize output over-voltage protection, but this kind of technical costs is higher, optocoupler is connected across the first and secondary inter-stage of power supply, need to take larger PCB (printed circuit board) space, and be a kind of overvoltage protection, function singleness, so design a kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit or necessary.
Utility model content
For the deficiency that prior art exists; the utility model object is to provide a kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit; cost is low; take up room little; efficiency and electromagnetic interference can not be affected simultaneously; be required for green energy conservation Switching Power Supply, good output over-voltage protection and overheat protector effect can be obtained, improve the safety and reliability of power supply.
To achieve these goals, the utility model realizes by the following technical solutions: a kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit, comprise transformer, IC chip, triode and field effect transistor, 4 pin of primary winding connect the drain electrode of field effect transistor, the positive pole of P1 termination the 3rd diode of transformer secondary output winding, the 3rd electric capacity is connected between the negative pole of the 3rd diode and the P2 of transformer secondary output winding hold, the positive pole of the 3rd electric capacity, negative pole meets power output end VOUT respectively, ground end AGND, the grid of field effect transistor connects 8 pin of the second resistance to IC chip, the source electrode of field effect transistor connects 6 pin of the 3rd resistance to IC chip, 4th resistance and the 5th resistance and after connecing with the second capacitance series at the 3rd resistance two ends, 2 pin of transformer feedback winding connect 7 pin of the first diode to IC chip, the first electric capacity is connected between the negative pole of the first diode and 1 pin of transformer feedback winding, the minus earth of the first electric capacity, 7 pin of IC chip connect the positive pole of the first resistance to the second diode, the negative pole of the second diode connects the negative pole of voltage stabilizing didoe, the positive pole of voltage stabilizing didoe connects the base stage of triode, the 4th electric capacity and the 6th resistance is connected between the base stage of triode and emitter, thermistor is connected between the emitter of triode and collector electrode, the grounded emitter of triode, the collector electrode of triode connects 5 pin of the 7th resistance to IC chip.
The beneficial effects of the utility model: cost is low; take up room little, can not affect efficiency and electromagnetic interference, be required for green energy conservation Switching Power Supply simultaneously; good output over-voltage protection and overheat protector effect can be obtained, improve the safety and reliability of power supply.
Accompanying drawing explanation
The utility model is described in detail below in conjunction with the drawings and specific embodiments;
Fig. 1 is background technology circuit diagram of the present utility model;
Fig. 2 is circuit diagram of the present utility model.
Embodiment
The technological means realized for making the utility model, creation characteristic, reaching object and effect is easy to understand, below in conjunction with embodiment, setting forth the utility model further.
With reference to Fig. 1-2, this embodiment is by the following technical solutions: a kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit, comprise transformer T1, IC chip U1, triode Q1 and field effect transistor Q2, 4 pin of transformer T1 armature winding connect the drain electrode of field effect transistor Q2, the positive pole of P1 termination the 3rd diode D3 of transformer T1 secondary winding, the 3rd electric capacity C3 is connected between the negative pole of the 3rd diode D3 and the P2 of transformer T1 secondary winding hold, the positive pole of the 3rd electric capacity C3, negative pole meets power output end VOUT respectively, ground end AGND, the grid of field effect transistor Q2 connects 8 pin of the second resistance R2 to IC chip U1, the source electrode of field effect transistor Q2 connects 6 pin of the 3rd resistance R3 to IC chip U1, 4th resistance R4 and the 5th resistance R5 is also serially connected in the 3rd resistance R3 two ends with the second electric capacity C2 after connecing, 2 pin of transformer T1 feedback winding connect 7 pin of the first diode D1 to IC chip U1, the first electric capacity C1 is connected between 1 pin that the negative pole of the first diode D1 and transformer T1 feed back winding, the minus earth of the first electric capacity C1, 7 pin of IC chip U1 connect the positive pole of the first resistance R1 to the second diode D2, the negative pole of the second diode D2 connects the negative pole of voltage stabilizing didoe ZD1, the positive pole of voltage stabilizing didoe ZD1 connects the base stage of triode Q1, the 4th electric capacity C4 and the 6th resistance R6 is connected between the base stage of triode Q1 and emitter, thermistor RT1 is connected between the emitter of triode Q1 and collector electrode, the grounded emitter of triode Q1, the collector electrode of triode Q1 connects 5 pin of the 7th resistance R7 to IC chip U1.
The operation principle of this embodiment: when electric power output voltage VOUT is higher, be coupled by transformer T1 secondary winding, feedback winding voltage raises, namely voltage VDD raises, simultaneously by the first resistance R1, the circuit for detecting conducting that first diode D1 and voltage stabilizing didoe ZD1 forms, first resistance R1 plays metering function, first diode D1 single direction flows to and utilizes its forward conduction voltage drop to do trim voltage, voltage stabilizing didoe ZD1 is to certain overvoltage and conducting, 4th electric capacity C4 starts punching electricity, namely the generation one voltage Vbe between the base stage of triode Q1 and emitter, thus triode Q1 conducting, the RT pin voltage of IC chip U1 is dragged down, RT pin voltage drags down and will IC chip U1 be made to be in protection, thus realize output voltage overvoltage protection, same for overheat protector, when power source temperature is too high, thermistor RT1 resistance increases with temperature and reduces, thus is dragged down by the RT pin voltage of IC chip U1, and IC chip U1 is in guard mode, realizes overheat protector.
This embodiment cost is low, takes up room little, can not affect efficiency and electromagnetic interference simultaneously, be required for green energy conservation Switching Power Supply, can obtain good output over-voltage protection and overheat protector effect, improve the safety and reliability of power supply.
More than show and describe general principle of the present utility model and principal character and advantage of the present utility model.The technical staff of the industry should understand; the utility model is not restricted to the described embodiments; what describe in above-described embodiment and specification just illustrates principle of the present utility model; under the prerequisite not departing from the utility model spirit and scope; the utility model also has various changes and modifications, and these changes and improvements all fall within the scope of claimed the utility model.The claimed scope of the utility model is defined by appending claims and equivalent thereof.

Claims (1)

1. a Switching Power Supply output over-voltage protection and thermal-shutdown circuit, it is characterized in that, comprise transformer (T1), IC chip (U1), triode (Q1) and field effect transistor (Q2), 4 pin of transformer (T1) armature winding connect the drain electrode of field effect transistor (Q2), the positive pole of the P1 termination the 3rd diode (D3) of transformer (T1) secondary winding, the 3rd electric capacity (C3) is connected between the negative pole of the 3rd diode (D3) and the P2 of transformer (T1) secondary winding hold, the positive pole of the 3rd electric capacity (C3), negative pole meets power output end VOUT respectively, ground end AGND, the grid of field effect transistor (Q2) connects 8 pin of the second resistance (R2) to IC chip (U1), the source electrode of field effect transistor (Q2) connects 6 pin of the 3rd resistance (R3) to IC chip (U1), 4th resistance (R4) and the 5th resistance (R5) are also serially connected in the 3rd resistance (R3) two ends with the second electric capacity (C2) after connecing, 2 pin that transformer (T1) feeds back winding connect 7 pin of the first diode (D1) to IC chip (U1), the first electric capacity (C1) is connected between 1 pin that the negative pole of the first diode (D1) and transformer (T1) feed back winding, the minus earth of the first electric capacity (C1), 7 pin of IC chip (U1) connect the positive pole of the first resistance (R1) to the second diode (D2), the negative pole of the second diode (D2) connects the negative pole of voltage stabilizing didoe (ZD1), the positive pole of voltage stabilizing didoe (ZD1) connects the base stage of triode (Q1), the 4th electric capacity (C4) and the 6th resistance (R6) is connected between the base stage of triode (Q1) and emitter, thermistor (RT1) is connected between the emitter of triode (Q1) and collector electrode, the grounded emitter of triode (Q1), the collector electrode of triode (Q1) connects 5 pin of the 7th resistance (R7) to IC chip (U1).
CN201420327410.2U 2014-06-19 2014-06-19 A kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit Expired - Fee Related CN204068678U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201420327410.2U CN204068678U (en) 2014-06-19 2014-06-19 A kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201420327410.2U CN204068678U (en) 2014-06-19 2014-06-19 A kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit

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CN204068678U true CN204068678U (en) 2014-12-31

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108365756A (en) * 2018-03-23 2018-08-03 佛山德仁照明科技有限公司 A kind of Switching Power Supply
CN111431146A (en) * 2020-05-09 2020-07-17 无锡雷利电子控制技术有限公司 Motor overvoltage and overheating protection system and motor and dish washing machine applying same
CN112003241A (en) * 2020-07-14 2020-11-27 宁波安信数控技术有限公司 Overcurrent and overvoltage protection circuit for switching power supply
CN112350279A (en) * 2020-09-02 2021-02-09 海信视像科技股份有限公司 Power supply protection circuit and electronic device

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108365756A (en) * 2018-03-23 2018-08-03 佛山德仁照明科技有限公司 A kind of Switching Power Supply
CN111431146A (en) * 2020-05-09 2020-07-17 无锡雷利电子控制技术有限公司 Motor overvoltage and overheating protection system and motor and dish washing machine applying same
CN111431146B (en) * 2020-05-09 2022-04-22 无锡雷利电子控制技术有限公司 Motor overvoltage and overheating protection system and motor and dish washing machine applying same
CN112003241A (en) * 2020-07-14 2020-11-27 宁波安信数控技术有限公司 Overcurrent and overvoltage protection circuit for switching power supply
CN112350279A (en) * 2020-09-02 2021-02-09 海信视像科技股份有限公司 Power supply protection circuit and electronic device
CN112350279B (en) * 2020-09-02 2022-06-28 海信视像科技股份有限公司 Power protection circuit and electronic device

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C14 Grant of patent or utility model
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CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20141231

Termination date: 20190619

CF01 Termination of patent right due to non-payment of annual fee