CN204349432U - A kind of Switching Power Supply thermal-shutdown circuit - Google Patents
A kind of Switching Power Supply thermal-shutdown circuit Download PDFInfo
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- CN204349432U CN204349432U CN201420805219.4U CN201420805219U CN204349432U CN 204349432 U CN204349432 U CN 204349432U CN 201420805219 U CN201420805219 U CN 201420805219U CN 204349432 U CN204349432 U CN 204349432U
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Abstract
The utility model discloses a kind of thermal-shutdown circuit of Switching Power Supply, it is characterized in that comprising 4 parts such as temperature sampling circuit 1, protective circuit 2, switching power source control circuit 3, DC bias supplies VCC end.Described temperature sampling circuit adopts a resistance and the series connection of thermistor, forms resitstance voltage divider, the temperature of temperature sampling circuit mainly sense switch power supply.Described protective circuit 2 comprises the first triode, the second triode, the first biasing resistor, the second biasing resistor; Control the control end com level of power supply control chip 3 according to the level of temperature sampling circuit output, complete Switching Power Supply defencive function.Input thermal-shutdown circuit described in the utility model can be applied in AC-DC, DC-DC Switching Power Supply, has circuit simply independent, can realize the advantages such as temperature hysteresis is arranged.
Description
Technical field
The utility model relates to a kind of Switching Power Supply thermal-shutdown circuit, particularly a kind of thermal-shutdown circuit of Switching Power Supply.
Prior art
In middle high power switching power supply application; due to a large amount of heatings of power device, cause the temperature of power supply very high, if the temperature of device is higher than the Limit temperature value of device; the damage of power supply will be caused, so overheat protector is one of necessary functions of middle large power supply.
This overheat protector function is realized in current application; substantially be all adopt to add thermistor near the device that temperature is the highest; carried out the shutoff of control switch power supply by thermistor change in resistance, common circuit as shown in Figure 1, adopts a thermistor series connection conventional, electric-resistance dividing potential drop to carry out detected temperatures; when the temperature increases; the resistance of thermistor reduces, and sampled voltage raises, and triode is switched to conducting state by off state; drag down the control port of control chip, Switching Power Supply is closed.This circuit realiration overheat protector is adopted mainly to there is following shortcoming; Can not complete self-locking when overheat protector action, frequent switching on and shutting down at the temperature of protection point annex, the long-term switch under this high temperature can cause Switching Power Supply reliability decrease.
Utility model content
The thermal-shutdown circuit of a kind of Switching Power Supply described in the utility model is achieved through the following technical solutions: a kind of thermal-shutdown circuit of Switching Power Supply, comprises temperature sampling circuit 1, protective circuit 2, switching power source control circuit 3, DC offset voltage Vcc hold.The input of temperature sampling circuit 1 connects input direct-current bias voltage Vcc end, and output is connected to the input A point of protective circuit 2, the control end com of the output connecting valve power supply of protective circuit 2.
Preferably, temperature sampling circuit 1 comprises thermistor, first resistance of series connection, forms resitstance voltage divider, and one end of thermistor connects DC offset voltage Vcc end, one end of another termination first resistance, the other end ground connection of the first resistance.
Preferably, protective circuit 2 comprises the first triode, second triode, first biasing resistor and the second biasing resistor, the base stage of the first triode is connected to the output A point of temperature sampling circuit 1, the emitter of the first triode is connected to the reference ground of circuit, the collector electrode of the first triode is connected to one end of the first biasing resistor, the other end of the first biasing resistor is connected to the control end com of switching power source control circuit, the base stage of the second triode is connected to the collector electrode of the first triode, the collector electrode of the second triode is connected to the output terminals A point of temperature sampling circuit 1, the emitter of the second triode is connected to one end of the second biasing resistor, the other end of the second biasing resistor is connected to the control end com of switching power source control circuit.
Preferably, the first triode is NPN triode.
Preferably, the second triode is PNP triode.
Further, a kind of thermal-shutdown circuit of Switching Power Supply also comprises bypass capacitor, and one end of shunt capacitance connects the output A of temperature sampling circuit, and other end connecting circuit is with reference to ground.
Thermal-shutdown circuit described in the utility model can be applied in AC-DC, DC-DC Switching Power Supply, has the advantages such as the return difference temperature that can arrange.
It is as follows with the return difference temperature principle that can arrange that the utility model realizes overheat protector;
Circuit as shown in Figure 2, when in control point being normal temperature work, the voltage that the output A point of temperature sampling circuit 1 collects is lower than the base stage threshold voltage of the first triode, and be operated in off state between the first transistor collector and emitter, no current flows through.First transistor collector level equals the level of Switching Power Supply control end com, and the second triode is also in off state, and Switching Power Supply control end com is high level state, and the control end com of protective circuit 2 pairs of Switching Power Supplies has no effect.When the temperature of tested measuring point raises; the resistance line of thermistor reduces; the output A level point also property line rising of temperature sampling circuit 1; when the temperature of test point reaches set overheat protector point; the A level point that temperature sampling circuit 1 exports reaches the base stage threshold level of the first triode, and the first triode produces I
b1electric current, has β * I between the collector electrode-emitter of the first triode
b1electric current flows through, and the first transistor collector level point reduces, and on the first biasing resistor, coating-forming voltage is poor, and this voltage difference, by the second biasing resistor, allows the second transistor emitter and base stage conducting produce base current I
b2, then produce collector electrode-emitter β * I
b2, this electric current continues the base level of raising first triode, forms positive feedback, and final formation protects self-locking.
The control end com of switching power source control circuit 3, the pass of its logic level and Switching Power Supply work is: high level Switching Power Supply normally works, and low level Switching Power Supply does not work.Generally com refers to the FEEDBACK CONTROL pin of control chip, is not limited thereto in the utility model, and they are all in can being meets high level Switching Power Supply and normally work, the control point that low level Switching Power Supply turns off.
Compared with prior art, the utility model has following outstanding advantage:
1. overheat protector can form self-locking;
2. return difference temperature can be set;
Overheat protector point: it is the monitoring temperature point that Switching Power Supply is closed that temperature raises;
Overheat protector recovery point: after overheat protector, Switching Power Supply temperature reduces the control point temperature of reworking.
Return difference temperature: overheat protector point temperature-overheat protector recovery point temperature
Accompanying drawing explanation
Fig. 1 is the thermal-shutdown circuit schematic diagram of prior art;
Fig. 2 is the circuit diagram of the utility model embodiment one;
Fig. 3 is the circuit diagram of the utility model embodiment two;
Embodiment
Case study on implementation one
The thermal-shutdown circuit of a kind of Switching Power Supply described in the utility model is achieved through the following technical solutions: a kind of thermal-shutdown circuit of Switching Power Supply, comprises temperature sampling circuit 1, protective circuit 2, switching power source control circuit 3, DC offset voltage Vcc hold.The input of temperature sampling circuit 1 connects input direct-current bias voltage Vcc end, and output is connected to the input A point of protective circuit 2, the control end com of the output connecting valve power control circuit of protective circuit 2.
Temperature sampling circuit 1 comprises thermistor RT, the first resistance R1 of series connection, forms resitstance voltage divider, and one end of thermistor RT connects DC offset voltage Vcc end, another termination first resistance R1, the other end ground connection of the first resistance R1.
Protective circuit 2 comprises the first triode Q1, second triode Q2, first biasing resistor R2 and the second biasing resistor R3, the base stage of the first triode Q1 is connected to the output A point of temperature sampling circuit 1, the emitter of the first triode Q1 is connected to the reference ground of circuit, the collector electrode of the first triode Q1 is connected to one end of the first biasing resistor R2, the other end of the first biasing resistor R2 is connected to the control end com of switching power source control circuit, the base stage of the second triode Q2 is connected to the collector electrode of the first triode Q1, the collector electrode of the second triode Q2 is connected to the output terminals A point of temperature sampling circuit 1, the emitter of the second triode Q2 is connected to one end of the one or two biasing resistor R3, the other end of the second biasing resistor R3 is connected to the control end com of Switching Power Supply.
Operation principle describes in detail in summary of the invention, does not repeat them here.
Second embodiment
Fig. 3 is the second embodiment circuit diagram of the present utility model, with embodiment one unlike adding shunt capacitance C1.One end of C1 connects the output A point of temperature sampling circuit, and other end connecting circuit is with reference to ground.The implementation case can solve Switching Power Supply noise larger time; easily interference voltage is formed at the output A point of temperature sampling circuit; this voltage easily causes protective circuit false triggering, and shunt capacitance C1 can effective filtering interfering voltage, ensures that thermal-shutdown circuit accurately completes overheat protector action.
Execution mode of the present utility model is not limited thereto according to foregoing of the present utility model; utilize ordinary technical knowledge and the customary means of this area; do not departing under the utility model above-mentioned basic fundamental thought prerequisite; in the utility model, concrete implementing circuit can also make the amendment of other various ways, replacement or change, all drops within the utility model rights protection scope.
Claims (4)
1. a Switching Power Supply thermal-shutdown circuit, it is characterized in that comprising temperature sampling circuit 1, protective circuit 2, switching power source control circuit 3, DC offset voltage VCC hold, the input of temperature sampling circuit 1 connects input direct-current bias voltage Vcc end, output is connected to the input A point of protective circuit 2, the control end com of the output connecting valve power control circuit of protective circuit 2;
Described temperature sampling circuit 1 comprises the first resistance and thermistor, forms resistor voltage divider circuit; One end of described thermistor connects DC offset voltage Vcc end, one end of first resistance described in another termination of described thermistor, the other end ground connection of the first described resistance;
Described protective circuit 2 comprises the first triode, the second triode, the first biasing resistor and the second biasing resistor; The base stage of the first described triode is connected to the output A point of temperature sampling circuit 1, and the emitter of the first described triode is connected to the reference ground of circuit, and the collector electrode of the first described triode is connected to one end of the first described biasing resistor; The other end of the first described biasing resistor is connected to the control end com of described switching power source control circuit; The base stage of the second described triode is connected to the collector electrode of the first described triode, the collector electrode of the second described triode is connected to the output terminals A point of described temperature sampling circuit 1, the emitter of the second described triode is connected to one end of described second biasing resistor, and the other end of the second described biasing resistor is connected to the control end com of switching power source control circuit.
2. a kind of Switching Power Supply thermal-shutdown circuit according to claim 1, is characterized in that: described DC offset voltage Vcc can adopt the inner any galvanic current pressure of Switching Power Supply.
3. a kind of Switching Power Supply thermal-shutdown circuit according to claim 1; it is characterized in that: described temperature sampling circuit 1 also comprises the first shunt capacitance; the output A of the temperature sampling circuit described in the connection of one end of the first described shunt capacitance, other end connecting circuit is with reference to ground.
4. a kind of Switching Power Supply thermal-shutdown circuit according to claim 1; it is characterized in that: the control end com of described switching power source control circuit 3; the pass of its logic level and Switching Power Supply work is: high level Switching Power Supply normally works, and low level Switching Power Supply does not work.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420805219.4U CN204349432U (en) | 2014-12-17 | 2014-12-17 | A kind of Switching Power Supply thermal-shutdown circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420805219.4U CN204349432U (en) | 2014-12-17 | 2014-12-17 | A kind of Switching Power Supply thermal-shutdown circuit |
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| CN204349432U true CN204349432U (en) | 2015-05-20 |
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| CN201420805219.4U Active CN204349432U (en) | 2014-12-17 | 2014-12-17 | A kind of Switching Power Supply thermal-shutdown circuit |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105162082A (en) * | 2015-08-25 | 2015-12-16 | 深圳市商宇电子科技有限公司 | Over-temperature protection circuit of uninterruptible power supply (UPS) charger |
| CN105375785A (en) * | 2015-10-22 | 2016-03-02 | 珠海格力电器股份有限公司 | Household electric appliance and switching power supply control circuit and method thereof |
| CN105372604A (en) * | 2015-08-25 | 2016-03-02 | 马瑞利汽车零部件(芜湖)有限公司 | LED automobile lamp test circuit with over-temperature protection instruction function |
| CN108303193A (en) * | 2018-04-10 | 2018-07-20 | 国家电网公司 | A kind of connecting terminal overheating detection circuit and single-phase charge-controlled intelligent electric meter |
| CN109375687A (en) * | 2018-10-17 | 2019-02-22 | 西安微电子技术研究所 | A kind of bipolar temperature observation circuit of Flouride-resistani acid phesphatase |
| CN109818343A (en) * | 2017-11-20 | 2019-05-28 | 深圳光峰科技股份有限公司 | A kind of overvoltage crowbar and projector |
| CN113872157A (en) * | 2021-10-09 | 2021-12-31 | 广州金升阳科技有限公司 | Hysteresis comparison control circuit |
-
2014
- 2014-12-17 CN CN201420805219.4U patent/CN204349432U/en active Active
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105162082A (en) * | 2015-08-25 | 2015-12-16 | 深圳市商宇电子科技有限公司 | Over-temperature protection circuit of uninterruptible power supply (UPS) charger |
| CN105372604A (en) * | 2015-08-25 | 2016-03-02 | 马瑞利汽车零部件(芜湖)有限公司 | LED automobile lamp test circuit with over-temperature protection instruction function |
| CN105372604B (en) * | 2015-08-25 | 2019-05-07 | 马瑞利汽车零部件(芜湖)有限公司 | A kind of LED car lamp test circuit with overheat protector instruction |
| CN105375785A (en) * | 2015-10-22 | 2016-03-02 | 珠海格力电器股份有限公司 | Household electric appliance and switching power supply control circuit and method thereof |
| CN109818343A (en) * | 2017-11-20 | 2019-05-28 | 深圳光峰科技股份有限公司 | A kind of overvoltage crowbar and projector |
| CN109818343B (en) * | 2017-11-20 | 2021-06-08 | 深圳光峰科技股份有限公司 | Overvoltage protection circuit and projector |
| CN108303193A (en) * | 2018-04-10 | 2018-07-20 | 国家电网公司 | A kind of connecting terminal overheating detection circuit and single-phase charge-controlled intelligent electric meter |
| CN108303193B (en) * | 2018-04-10 | 2023-11-07 | 国家电网公司 | Binding post overheat detection circuit and single-phase charge control intelligent ammeter |
| CN109375687A (en) * | 2018-10-17 | 2019-02-22 | 西安微电子技术研究所 | A kind of bipolar temperature observation circuit of Flouride-resistani acid phesphatase |
| CN113872157A (en) * | 2021-10-09 | 2021-12-31 | 广州金升阳科技有限公司 | Hysteresis comparison control circuit |
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