CN205070404U - Short-circuit protection circuit and switching power supply circuit - Google Patents
Short-circuit protection circuit and switching power supply circuit Download PDFInfo
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- CN205070404U CN205070404U CN201520843200.3U CN201520843200U CN205070404U CN 205070404 U CN205070404 U CN 205070404U CN 201520843200 U CN201520843200 U CN 201520843200U CN 205070404 U CN205070404 U CN 205070404U
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Abstract
The utility model discloses a short-circuit protection circuit, including reference voltage collection end, short-circuit protection output, earthing terminal, reference voltage bleeder circuit and voltage reference IC, through the abnormal voltage signal that produces the heavy current and cause among the reference voltage collection end acquisition circuit because of taking place the short circuit, whether control voltage reference IC switches on, passes through short-circuit protection output with short circuit or normal information and exports, circuit structure is simple, can be timely, trigger protect function effectively. The utility model discloses still disclose an utilize above-mentioned short-circuit protection circuit's switching power supply circuit, switching power supply control chip among this switching power supply circuit has low pressure and triggers the protection end, and above-mentioned short-circuit protection output is connected with this low pressure and triggers the protection end, and when power output end or transformer short circuit, short-circuit protection circuit provides low-voltage signal and triggers the protection end for the low pressure, in time turn-offs the switch tube, prevents that too big electric current from damaging the switch tube, has protected power supply circuit.
Description
Technical field
The utility model relates to electronic technology field, particularly relates to a kind of short-circuit protection circuit and switching power circuit.
Background technology
Power circuit is as the supply line of electronic product, and except performance will meet application requirement, the safeguard measure of himself is also extremely important, as overvoltage, overcurrent, overtemperature protection etc.Once supply line's output short circuit of electronic product, must close its input current in time, the electronic component in ability protective circuit is not burnt, otherwise may cause the further damage of electronic product, even causes safety issue.
In order to ensure stability, the reliability of circuit in prior art; usually sampling monitoring can be carried out to the input or output current; by in the control unit of sampled signal input circuit; real-time control circuit operates; namely can when output be short-circuited; obtain abnormal information according to sampled signal, control circuit input current reduces, and keeps stable.But sampled signal often will after filtering after just can import control unit into, filter circuit has time delay usually; And multiple numerical value that the exportable amplitude of sample circuit is different, control unit, to the process more complicated of sampled signal, can not obtain short circuit or normal signal and trigger protection function simply, rapidly.
Common switching power circuit as shown in Figure 1, power input is connected with the first end of the primary coil of transformer T1, power output end is connected with the secondary coil of transformer T1, the first end of the second end connecting valve pipe Q1 of the primary coil of transformer T1, second end of switching tube Q1 connects the first end of sample circuit Rs, the second end ground connection of sample circuit Rs, the square wave that switching tube Q1 exports by Switching Power Supply control chip controls, Switching Power Supply control chip is by obtaining the magnitude of voltage on sample circuit Rs first end, adjustment exports the duty ratio of square wave to reduce or to increase the ON time of switching tube, maintain the stable of output current.The signal waveform causing sample circuit Rs to export to prevent interference signal in circuit, with spine, ensures the accuracy of sampling, and sample circuit Rs is usually by low-pass filter circuit connecting valve power supply control chip.When power output end or transformer short-circuit, electric current sharply rises, because the general comparatively input waveform of low-pass filter circuit output waveform has time delay, and also there is time delay Switching Power Supply control chip inside to the process of sampled signal, can not rapid triggering switching power source chip, driving switch pipe Q1 disconnects, electric current in the current branch of the therefore primary coil of transformer T1, switching tube Q1, sample circuit Rs can than much larger during normal work, be easy to cause switching tube Q1 to damage, thus cause power supply to damage.
Utility model content
The purpose of this utility model is to provide a kind of short-circuit protection circuit and switching power circuit, overcomes in circuit and causes because being short-circuited electric current to increase, and causes the problem that electronic component damages, power supply damages, improves stability, the reliability of circuit working.
To achieve these goals, the utility model provides a kind of short-circuit protection circuit, comprises reference voltage collection terminal, short-circuit protection output, earth terminal, reference voltage bleeder circuit and voltage reference IC;
Described reference voltage bleeder circuit comprises first end, dividing potential drop node and the second end; The first end of described reference voltage bleeder circuit connects described reference voltage collection terminal, and the second end of described reference voltage bleeder circuit connects described earth terminal;
Described voltage reference IC comprises negative electrode, anode and reference pole; The reference pole of described voltage reference IC connects the dividing potential drop node of described reference voltage bleeder circuit, and the negative electrode of described voltage reference IC connects described short-circuit protection output, and the anode of described voltage reference IC connects described earth terminal.
Preferably, described reference voltage bleeder circuit comprises the first resistance and second resistance of series connection;
The first end of described first resistance is the first end of described reference voltage bleeder circuit, and the second end of described first resistance connects the first end of described second resistance, and the second end of described second resistance is the second end of described reference voltage bleeder circuit; The tie point of described first resistance and the second resistance is described dividing potential drop node.
Preferably, described short-circuit protection circuit also comprises the first electric capacity, and described first electric capacity is connected between the negative electrode of described voltage reference IC and reference pole.
Further, described short-circuit protection circuit also comprises the 3rd resistance; The negative electrode of described voltage reference IC connects described short-circuit protection output, is specially: the negative electrode of described voltage reference IC connects described short-circuit protection output by described 3rd resistance.
Meanwhile, the utility model also provides a kind of switching power circuit, comprises power input, power output end, transformer, switching tube, Switching Power Supply control chip, sample circuit, low-pass filter circuit and above-mentioned short-circuit protection circuit;
Described power input is connected with the first end of the primary coil of described transformer, and described power output end is connected with the secondary coil of described transformer;
Second end of the primary coil of described transformer connects the first end of described switching tube, and the second end of described switching tube connects the first end of described sample circuit, the second end ground connection of described sample circuit;
Described Switching Power Supply control chip comprises drive singal output, current sample input and low pressure trigger protection end; Described drive singal output connects the control end of described switching tube;
The input of described low-pass filter circuit connects the first end of sample circuit, and the output of described low-pass filter circuit connects described current sample input;
The reference voltage collection terminal of described short-circuit protection circuit connects the output of described low-pass filter circuit, and the short-circuit protection output of described short-circuit protection circuit connects described low pressure trigger protection end, the earth terminal ground connection of described short-circuit protection circuit.
Preferably, described switching tube is N-type field effect transistor, and the grid of described N-type field effect transistor is the control end of described switching tube, and the drain electrode of described N-type field effect transistor is the first end of described switching tube, and the source electrode of described N-type field effect transistor is the second end of described switching tube.
Implement the utility model, have following beneficial effect:
The short-circuit protection circuit that the utility model provides; by reference to the abnormal voltage signal producing big current in voltage acquisition end acquisition cuicuit because being short-circuited and cause; whether control voltage benchmark IC conducting; short circuit or normal information are exported by short-circuit protection output; circuit structure is simple, can in time, trigger protection function effectively.
The switching power circuit that the utility model provides, obtains the magnitude of voltage on sample circuit first end by Switching Power Supply control chip, and the time scale of adjustment switching tube conducting and cut-off, maintains stable output signal; When power output end or transformer short-circuit; short-circuit protection circuit obtains too high voltage signal by reference to voltage acquisition end; and this signal is converted into the low pressure trigger protection end that low-voltage signal is sent to switching power source chip; thus make the timely on-off switching tube of switching power source chip; prevent electric current from continuing to increase damage switching tube; protect power supply, improve stability, the reliability of circuit.
Accompanying drawing explanation
Fig. 1 is the circuit theory diagrams of existing switching power circuit;
Fig. 2 is the schematic diagram of an embodiment of the short-circuit protection circuit that the utility model provides;
Fig. 3 is the circuit block diagram of the switching power circuit that the utility model provides;
Fig. 4 is the circuit theory diagrams of an embodiment of the switching power circuit that the utility model provides.
Embodiment
Below in conjunction with the accompanying drawing in the utility model embodiment, be clearly and completely described the technical scheme in the utility model embodiment, obviously, described embodiment is only the utility model part embodiment, instead of whole embodiments.Based on the embodiment in the utility model, those of ordinary skill in the art are not making the every other embodiment obtained under creative work prerequisite, all belong to the scope of the utility model protection.
See Fig. 2, it is the schematic diagram of an embodiment of the short-circuit protection circuit that the utility model provides;
Short-circuit protection circuit 201 comprises reference voltage collection terminal b, short-circuit protection output c, earth terminal d, the first resistance R1, the second resistance R2, voltage reference ICU2, the first electric capacity C1, the 3rd resistance R3.First resistance R1 connects with the second resistance R2 and forms reference voltage bleeder circuit, and this reference voltage bleeder circuit comprises first end, dividing potential drop node e and the second end; The first end of the first resistance R1 is the first end of this reference voltage bleeder circuit, and the second end of the first resistance connects the first end of the second resistance R2, and second end of the second resistance R2 is the second end of this reference voltage bleeder circuit; The first end of reference voltage bleeder circuit connects described reference voltage collection terminal b, and the second end of reference voltage bleeder circuit connects earth terminal d; First resistance R1, the second resistance R2 series connection carry out dividing potential drop to reference voltage, and the tie point of the first resistance R1 and the second resistance R2 is dividing potential drop node e; Voltage reference ICU2 comprises negative electrode K, anode A and reference pole R, connects this dividing potential drop node e, obtain reference voltage partial pressure value with reference to pole R.The negative electrode K of voltage reference ICU2 connects short-circuit protection output c by the 3rd resistance R3, and anode connects earth terminal d.First electric capacity C1 is connected to the negative electrode of voltage reference ICU2 and with reference between pole, the first electric capacity C1, to voltage reference ICU2 redeeming, improves the response speed of voltage reference IC.
When circuit normally works and is short-circuited; voltage on dividing potential drop node e compares from the voltage reference value of voltage reference ICU2 and has different results; therefore can the ICU2 conducting of control voltage benchmark or cut-off, short-circuit protection output can be controlled in time, exactly and export two different magnitudes of voltage in both cases.
The short-circuit protection circuit that the utility model provides; by reference to the abnormal voltage signal producing big current in voltage acquisition end acquisition cuicuit because being short-circuited and cause; whether control voltage benchmark IC conducting; short circuit or normal information are exported by short-circuit protection output; circuit structure is simple, can in time, trigger protection function effectively.
See Fig. 3, it is the circuit block diagram of the switching power circuit that the utility model provides.
This switching power circuit comprises power input Vin, power output end Vout, transformer T1, switching tube Q1, Switching Power Supply control chip U1, sample circuit Rs, low-pass filter circuit 202 and short-circuit protection circuit 201;
Described power input Vin is connected with the first end of the primary coil of described transformer T1, and described power output end Vout is connected with the secondary coil of described transformer T1;
Second end of the primary coil of described transformer T1 connects the first end of described switching tube Q1, and second end of described switching tube Q1 connects the first end of described sample circuit Rs, the second end ground connection of described sample circuit Rs;
Described Switching Power Supply control chip comprises drive singal output GATE, current sample input CS and low pressure trigger protection end NC; Described drive singal output connects the control end of described switching tube Q1;
The input of described low-pass filter circuit 202 connects the first end of sample circuit Rs, and the output of described low-pass filter circuit 202 connects described current sample input CS;
The reference voltage collection terminal b of described short-circuit protection circuit 201 connects the output of described low-pass filter circuit 202, and described short-circuit protection output c connects described low pressure trigger protection end NC, described earth terminal ground connection.
Switching Power Supply control chip has low pressure trigger protection end NC; under normal operating conditions, low pressure trigger protection end should be designed to connect high voltage; when circuit abnormality; low pressure trigger protection end NC connects low-voltage; thus the defencive function of trigger switch power supply control chip U1; switching tube Q1 is disconnected, in the utility model, provides voltage signal to low pressure trigger protection end NC by short-circuit protection circuit 201.When power output end or transformer short-circuit; short-circuit protection circuit 201 obtains voltage signal too high on sample circuit Rs by reference to voltage acquisition end b; and this signal is converted into the low pressure trigger protection end NC that low-voltage signal is sent to switching power source chip U1; make Switching Power Supply control chip U1 no-output; thus switching tube Q1 disconnects; prevent electric current from continuing to increase damage switching tube Q1, protect power supply, improve stability, the reliability of circuit.
See Fig. 4, be the circuit theory diagrams of an embodiment of the switching power circuit that the utility model provides.As shown in Figure 4, switching tube Q1 is N-type field effect transistor, the control end of switching tube, first end and the second end, corresponding to the grid of N-type field effect transistor, drain electrode, source electrode.The operation principle of Switching Power Supply control chip U1 is: the drive singal output GATE's of Switching Power Supply control chip U1 is output-controlled in the voltage of current sample input CS and the comparative result of a certain voltage threshold, export square-wave signal, if current sample input CS voltage is more higher than voltage threshold, then the duty ratio (ratio in the duration of positive pulse and pulse total cycle) of drive singal output GATE output signal is less, otherwise then larger.
In the present embodiment, low-pass filter circuit 202 is RC filter circuit, comprise the 4th resistance R4 and the second electric capacity C2, the first end of the 4th resistance R4 is the input of low-pass filter circuit 202, second end is the output of low-pass filter circuit 202, the first end of the second electric capacity C2 connects the output of low-pass filter circuit 202, the second end ground connection.
In the present embodiment; the first resistance R1 in short-circuit protection circuit 201, the second resistance R2 series connection carry out dividing potential drop to reference voltage; it is rear in parallel with sample circuit Rs that essence is the first resistance R1, the second resistance R2, the 4th resistance R4 connects; carry out dividing potential drop to sample circuit Rs, dividing potential drop node e obtains the partial pressure value of sample circuit Rs.When circuit normally works, on dividing potential drop node, the voltage of e is lower than the voltage reference value of voltage reference ICU2, therefore voltage reference ICU2 ends, because low pressure trigger protection end NC is internally connected with voltage source at Switching Power Supply control chip, now the magnitude of voltage of low pressure trigger protection end NC is the magnitude of voltage of this voltage source, higher than the internal reference voltage of Switching Power Supply control chip U1, therefore not trigger protection function, circuit normally works;
When power output end or transformer short-circuit; electric current in the current branch of the primary coil of transformer T1, switching tube Q1, sample circuit Rs can than much larger during normal work; voltage on dividing potential drop node is higher than the voltage reference value of voltage reference ICU2; therefore voltage reference ICU2 conducting; ground connection after now internal source voltage connection the 3rd resistance R3, voltage reference ICU2; the magnitude of voltage of low pressure trigger protection end NC is dragged down; therefore the defencive function of flip chip; Switching Power Supply control chip U1 no-output; switching tube Q1 disconnects, and avoids continuing current flow and increases.
It should be noted that, in the switching power circuit that above-described embodiment provides, switching tube Q1 is N-type field effect transistor, be only a kind of execution mode wherein, in other embodiments, switching tube Q1 can also replace with NPN type triode or other three ends control switch device or its and derive from device, in different application scenarios, depending on side circuit power consumption, cost, driving power and require reasonable selection and setting with the drived control component parameter matching etc. of switching tube, select and the conventional design process that switching tube is prior art is set, not repeating at this; Low-pass filter circuit 202 is also only wherein a kind of execution mode for RC filter circuit, in other embodiments, other low-pass filter circuits such as LC filter circuit can also be replaced with, when adopting LC filter circuit, the 4th resistance R4 in above-described embodiment is only needed to replace with inductance element, what these low-pass filter circuit structures adopted is all the conventional design of prior art, does not repeat one by one at this.
The switching power circuit that the utility model provides, obtains the magnitude of voltage on sample circuit first end by Switching Power Supply control chip, and the time scale of adjustment switching tube conducting and cut-off, maintains stable output signal; When power output end or transformer short-circuit; short-circuit protection circuit obtains too high voltage signal by reference to voltage acquisition end; and this signal is converted into the low pressure trigger protection end that low-voltage signal is sent to switching power source chip; thus make the timely on-off switching tube of switching power source chip; prevent electric current from continuing to increase damage switching tube; protect power supply, improve stability, the reliability of circuit.
The above is preferred implementation of the present utility model; it should be pointed out that for those skilled in the art, under the prerequisite not departing from the utility model principle; can also make some improvement and distortion, these improve and distortion is also considered as protection range of the present utility model.
Claims (6)
1. a short-circuit protection circuit, is characterized in that, comprises reference voltage collection terminal, short-circuit protection output, earth terminal, reference voltage bleeder circuit and voltage reference IC;
Described reference voltage bleeder circuit comprises first end, dividing potential drop node and the second end; The first end of described reference voltage bleeder circuit connects described reference voltage collection terminal, and the second end of described reference voltage bleeder circuit connects described earth terminal;
Described voltage reference IC comprises negative electrode, anode and reference pole; The reference pole of described voltage reference IC connects the dividing potential drop node of described reference voltage bleeder circuit, and the negative electrode of described voltage reference IC connects described short-circuit protection output, and the anode of described voltage reference IC connects described earth terminal.
2. short-circuit protection circuit as claimed in claim 1, it is characterized in that, described reference voltage bleeder circuit comprises the first resistance and second resistance of series connection;
The first end of described first resistance is the first end of described reference voltage bleeder circuit, and the second end of described first resistance connects the first end of described second resistance, and the second end of described second resistance is the second end of described reference voltage bleeder circuit; The tie point of described first resistance and the second resistance is described dividing potential drop node.
3. short-circuit protection circuit as claimed in claim 1 or 2, it is characterized in that, described short-circuit protection circuit also comprises the first electric capacity, and described first electric capacity is connected between the negative electrode of described voltage reference IC and reference pole.
4. short-circuit protection circuit as claimed in claim 1 or 2, it is characterized in that, described short-circuit protection circuit also comprises the 3rd resistance;
The negative electrode of described voltage reference IC connects described short-circuit protection output, is specially: the negative electrode of described voltage reference IC connects described short-circuit protection output by described 3rd resistance.
5. a switching power circuit, is characterized in that, comprises power input, power output end, transformer, switching tube, Switching Power Supply control chip, sample circuit, low-pass filter circuit and the short-circuit protection circuit as described in any one of Claims 1-4;
Described power input is connected with the first end of the primary coil of described transformer, and described power output end is connected with the secondary coil of described transformer;
Second end of the primary coil of described transformer connects the first end of described switching tube, and the second end of described switching tube connects the first end of described sample circuit, the second end ground connection of described sample circuit;
Described Switching Power Supply control chip comprises drive singal output, current sample input and low pressure trigger protection end; Described drive singal output connects the control end of described switching tube;
The input of described low-pass filter circuit connects the first end of sample circuit, and the output of described low-pass filter circuit connects described current sample input;
The reference voltage collection terminal of described short-circuit protection circuit connects the output of described low-pass filter circuit, and the short-circuit protection output of described short-circuit protection circuit connects described low pressure trigger protection end, the earth terminal ground connection of described short-circuit protection circuit.
6. switching power circuit as claimed in claim 5, it is characterized in that, described switching tube is N-type field effect transistor, the grid of described N-type field effect transistor is the control end of described switching tube, the drain electrode of described N-type field effect transistor is the first end of described switching tube, and the source electrode of described N-type field effect transistor is the second end of described switching tube.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520843200.3U CN205070404U (en) | 2015-10-27 | 2015-10-27 | Short-circuit protection circuit and switching power supply circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520843200.3U CN205070404U (en) | 2015-10-27 | 2015-10-27 | Short-circuit protection circuit and switching power supply circuit |
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| CN205070404U true CN205070404U (en) | 2016-03-02 |
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| CN201520843200.3U Active CN205070404U (en) | 2015-10-27 | 2015-10-27 | Short-circuit protection circuit and switching power supply circuit |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106711939A (en) * | 2017-03-14 | 2017-05-24 | 惠州市忠邦电子有限公司 | Protective circuit capable of preventing short circuit or micro-short circuit or touch-caused spark of direct-current power supply |
| CN107144798A (en) * | 2017-06-21 | 2017-09-08 | 杰华特微电子（张家港）有限公司 | Abnormal detection circuit and method and Switching Power Supply |
| CN109546847A (en) * | 2019-01-16 | 2019-03-29 | 合肥惠科金扬科技有限公司 | Synchronization breaking circuit, driving circuit and the synchronous cut-off method of Switching Power Supply |
| US10367348B2 (en) | 2015-11-26 | 2019-07-30 | Byd Company Limited | Switch-mode power supply and control having protection from a short-circuited current sensing resistor |
| CN111327023A (en) * | 2020-04-07 | 2020-06-23 | 广州致远电子有限公司 | Output short-circuit protection circuit and switching power supply control system |
-
2015
- 2015-10-27 CN CN201520843200.3U patent/CN205070404U/en active Active
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10367348B2 (en) | 2015-11-26 | 2019-07-30 | Byd Company Limited | Switch-mode power supply and control having protection from a short-circuited current sensing resistor |
| CN106711939A (en) * | 2017-03-14 | 2017-05-24 | 惠州市忠邦电子有限公司 | Protective circuit capable of preventing short circuit or micro-short circuit or touch-caused spark of direct-current power supply |
| CN107144798A (en) * | 2017-06-21 | 2017-09-08 | 杰华特微电子（张家港）有限公司 | Abnormal detection circuit and method and Switching Power Supply |
| CN107144798B (en) * | 2017-06-21 | 2024-03-19 | 杰华特微电子（张家港）有限公司 | Abnormality detection circuit and method and switching power supply |
| CN109546847A (en) * | 2019-01-16 | 2019-03-29 | 合肥惠科金扬科技有限公司 | Synchronization breaking circuit, driving circuit and the synchronous cut-off method of Switching Power Supply |
| CN111327023A (en) * | 2020-04-07 | 2020-06-23 | 广州致远电子有限公司 | Output short-circuit protection circuit and switching power supply control system |
| CN111327023B (en) * | 2020-04-07 | 2022-07-08 | 广州致远电子有限公司 | Output short-circuit protection circuit and switching power supply control system |
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