CN101752829B - Undervoltage protection circuit and switching power supply - Google Patents
Undervoltage protection circuit and switching power supply Download PDFInfo
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- CN101752829B CN101752829B CN200910189204.3A CN200910189204A CN101752829B CN 101752829 B CN101752829 B CN 101752829B CN 200910189204 A CN200910189204 A CN 200910189204A CN 101752829 B CN101752829 B CN 101752829B
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Abstract
The invention is suitable for the field of switching power supplies, and provides an undervoltage protection circuit and a switching power supply. The undervoltage protection circuit comprises a comparison circuit, a switching circuit, a delay loop circuit and a voltage stabilizing circuit. In the invention, the direct voltage required by the undervoltage protection circuit is directly taken from the direct voltage after the switching power supply inputs the alternating current for rectification without adding transformers or the windings of the transformer, thereby saving the space for the circuit board and reducing the power consumption of the whole circuit. In addition, the undervoltage protection circuit controls the output of the shutdown switch power supply of the switching power supply chip, thereby avoiding realizing the on-off state by adding switching tubes or relays to the output end of the switching power supply, reducing the power consumption, saving the space and enhancing the reliability.
Description
Technical field
The invention belongs to field of switch power, relate in particular to a kind of under-voltage protecting circuit and Switching Power Supply.
Background technology
Because of energy-saving and environmental protection, the advantage such as efficient, Switching Power Supply has been widely used in various electric equipment products.In the middle of practical application, General Requirements Switching Power Supply has under-voltage protection function.
The realization of under-voltage protection function is generally to be realized by special switching power source chip.But this chip is all generally the input of wide power voltage; as 85～265VAC; and in some application scenario, as emergency lighting occasion, require being not less than 0.6 times of rated supply voltage and during not higher than 0.85 times of rated supply voltage; will power cutoff voltage; for example, rated voltage is 220VAC, when input voltage drops to 132～187VAC so; will carry out under-voltage protection, power cutoff voltage.Obviously, in these occasions, it is inadequate only depending on chip itself to carry out under-voltage protection, must access control circuit.
For above-mentioned application, also there is the under-voltage protecting circuit of this respect.But in these circuit, all first to produce the required direct voltage of circuit by transformer coupled, rectifying and wave-filtering, pass through again the variation of comparison circuit monitoring power voltage, the conducting of the height control switch pipe of amplifier output level or the adhesive of relay, and then the break-make of control switch power supply.These circuit becauses have increased transformer or Transformer Winding, and output circuit has increased relay or switching tube, thereby have increased the size of wiring board and the power consumption of whole circuit, have reduced the reliability of circuit.
Summary of the invention
The object of the embodiment of the present invention is to provide a kind of under-voltage protecting circuit, is intended to solve existing under-voltage protecting circuit and has power consumption greatly and the problem of poor reliability.
The embodiment of the present invention is achieved in that a kind of under-voltage protecting circuit, and described circuit comprises:
The comparison circuit being connected with the output of current rectifying and wave filtering circuit, input voltage and the reference voltage of described current rectifying and wave filtering circuit output are compared, if input voltage is less than reference voltage, represent that power input voltage is under-voltage, described comparison circuit output under-voltage protection control signal;
The switching circuit being connected with the output of described comparison circuit, according to the under-voltage protection control signal of described comparison circuit output, the output of control switch power supply chip stopcock power supply;
The sluggish loop being connected with described comparison circuit, controls described comparison circuit, deepens and accelerate the upset of comparison circuit; And
Respectively with the output of described current rectifying and wave filtering circuit, and the voltage stabilizing circuit that is connected of the power end of comparison circuit, switching circuit and sluggish loop;
Described comparison circuit comprises: parallel voltage-stabilizing diode A1 able to programme, capacitor C 2, the second bleeder circuit, capacitor C 3 that model is TL431;
Described the second bleeder circuit comprises resistance R 5, resistance R 6, resistance R 7, the resistance R 8 of series connection successively and the resistance R 9 being connected with the public connecting end of described resistance R 5 and described resistance R 6, the control utmost point of parallel voltage-stabilizing diode A1 able to programme described in the first termination of described resistance R 5, the output of a termination current rectifying and wave filtering circuit of described resistance R 8;
The anode of described parallel voltage-stabilizing diode A1 able to programme connects the power end of described comparison circuit by capacitor C 2, the negative electrode of described parallel voltage-stabilizing diode A1 able to programme connects the input of described switching circuit; The anode of parallel voltage-stabilizing diode A1 able to programme described in the first termination of described capacitor C 3, the second end of resistance R 5 described in the second termination of described capacitor C 3;
Described sluggish loop comprises resistance R 10, resistance R 11, the second triode Q2 and resistance R 12, the base stage of the second triode Q2 described in the first termination of described resistance R 10, the power end of sluggish loop described in the second termination of described resistance R 10, the base stage of the second triode Q2 described in the first termination of described resistance R 11, the second end ground connection of described resistance R 11, the collector electrode of the second triode Q2 described in the first termination of described resistance R 12, the second end ground connection of described resistance R 12; The collector electrode of described the second triode Q2 connects resistance R 9 described in described the second bleeder circuit.
Another object of the embodiment of the present invention is to provide a kind of Switching Power Supply, and it comprises current rectifying and wave filtering circuit and switching power source chip, and described Switching Power Supply also comprises above-mentioned under-voltage protecting circuit.
In embodiments of the present invention; the required direct voltage of this under-voltage protecting circuit is directly taken from the direct voltage after Switching Power Supply input AC electric rectification; press without carrying out power taking by the winding that increases transformer or the existing transformer of increase; save the space of wiring board; also reduce the power consumption of whole circuit; in addition; this under-voltage protecting circuit is by the output of control switch power supply chip stopcock power supply; avoid realizing break-make at output increase switching tube or the relay of Switching Power Supply; reduce power consumption; save space, improved reliability.
Brief description of the drawings
Fig. 1 is the structure chart of the switch power supply under-voltage protecting circuit that provides of the embodiment of the present invention;
Fig. 2 is the exemplary circuit figure of the switch power supply under-voltage protecting circuit that provides of the embodiment of the present invention.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearer, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.
Fig. 1 shows the structure of the switch power supply under-voltage protecting circuit that the embodiment of the present invention provides, and for convenience of explanation, only shows the part relevant to the embodiment of the present invention.
Switching Power Supply comprises current rectifying and wave filtering circuit, switching power source chip, transformer and output circuit; Switching Power Supply also comprises under-voltage protecting circuit; under-voltage protecting circuit comprises the comparison circuit 300 being connected with the output of current rectifying and wave filtering circuit, the switching circuit 400 being connected with the output of comparison circuit 300, the sluggish loop 200 being connected with comparison circuit 300; and respectively with the output of current rectifying and wave filtering circuit, and the voltage stabilizing circuit 100 that is connected of comparison circuit 300, switching circuit 400 and the power end of sluggish loop 200.
The under-voltage protection control signal that switching circuit 400 is exported according to comparison circuit 300, the output of control switch power supply chip stopcock power supply;
Sluggish loop 200 is controlled comparison circuit 300, deepens and accelerate the upset of comparison circuit 300, improves the stability of circuit working;
Fig. 2 shows the exemplary circuit structure of the switch power supply under-voltage protecting circuit that the embodiment of the present invention provides, and for convenience of explanation, only shows the part relevant to the embodiment of the present invention.
As one embodiment of the invention, the first switching tube 101 is the first triode Q1, the collector electrode of the first triode Q1 connects the output of current rectifying and wave filtering circuit, the base stage of the first triode Q1 connects the output of current rectifying and wave filtering circuit by the first bleeder circuit 102, wherein, the first bleeder circuit 102 comprises resistance R 1, resistance R 2, resistance R 3 and the diode D1 of series connection successively, the output of one termination current rectifying and wave filtering circuit of resistance R 1, the plus earth of diode D1, the public connecting end of resistance R 3 and diode D1 negative electrode connects the base stage of the first triode Q1.The emitter of the first triode Q1 meets the power end VCC of comparison circuit 300, switching circuit 400 and sluggish loop 200.
As one embodiment of the invention, it is the parallel voltage-stabilizing diode A1 able to programme of TL431 that comparator 301 adopts model, the control utmost point of parallel voltage-stabilizing diode A1 able to programme connects the output of current rectifying and wave filtering circuit by the second bleeder circuit 302, the anode of parallel voltage-stabilizing diode A1 able to programme meets the power end VCC of comparison circuit 300 by capacitor C 2, the negative electrode of parallel voltage-stabilizing diode A1 able to programme connects the input of switching circuit 400, wherein, the second bleeder circuit 302 comprises the resistance R 5 of series connection successively, resistance R 6, resistance R 7, resistance R 8, and the resistance R 9 being connected with the public connecting end of resistance R 5 and resistance R 6, the control utmost point of the first termination parallel voltage-stabilizing diode able to programme A1 of resistance R 5, the output of one termination current rectifying and wave filtering circuit of resistance R 8.
Sluggish loop 200 comprises second switch pipe 201, the power end VCC on the input termination hysteresis loop road 200 of second switch pipe 201, the second bleeder circuit 302 of the output termination comparison circuit 300 of second switch pipe 201.
As one embodiment of the invention, second switch pipe 201 is the second triode Q2, the base stage of the second triode Q2 meets the power end VCC of sluggish loop 200, and the collector electrode of the second triode Q2 connects the grounded emitter of the second bleeder circuit 302, the second triode Q2 of comparison circuit 300.
Sluggish loop 200 also comprises resistance R 10, resistance R 11 and resistance R 12, the base stage of first termination the second triode Q2 of resistance R 10, the power end VCC of the sluggish loop 200 of the second termination of resistance R 10, the base stage of first termination the second triode Q2 of resistance R 11, the second end ground connection of resistance R 11, the collector electrode of first termination the second triode Q2 of resistance R 12, the second end ground connection of resistance R 12.
As one embodiment of the invention, the 3rd switching tube 401 adopts MOSFET pipe Q3, the grid of MOSFET pipe Q3 meets respectively the output of comparator 301 and the power end VCC of switching circuit 400 by the 3rd bleeder circuit 402, the drain electrode of MOSFET pipe Q3 connects switching power source chip, the source ground of MOSFET pipe Q3, wherein, the 3rd bleeder circuit 402 comprises resistance R 13 and resistance R 14, the power end VCC of the first termination switching circuit 400 of resistance R 13, the second end of resistance R 13 is the first end of connecting resistance R14 and the grid of MOSFET pipe Q3 respectively, the second end ground connection of resistance R 14.
Its operation principle is:
In the time that Switching Power Supply AC-input voltage reduces; comparison circuit 300 compares input voltage and the reference voltage of current rectifying and wave filtering circuit output; if input voltage is less than reference voltage; represent that AC-input voltage is under-voltage; comparison circuit 300 is exported under-voltage protection control signal; the under-voltage protection control signal that switching circuit 400 is exported according to comparison circuit 300, the output of control switch power supply chip stopcock power supply, thus play the effect of under-voltage protection.
In embodiments of the present invention; the required direct voltage of this under-voltage protecting circuit is directly taken from the direct voltage after Switching Power Supply input AC electric rectification; press without carrying out power taking by the winding that increases transformer or the existing transformer of increase; save the space of wiring board; also reduce the power consumption of whole circuit; in addition; this under-voltage protecting circuit is by the output of control switch power supply chip stopcock power supply; avoid realizing break-make at output increase switching tube or the relay of Switching Power Supply; reduce power consumption; save space, improved reliability.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.
Claims (6)
1. a under-voltage protecting circuit, is characterized in that, described circuit comprises:
The comparison circuit being connected with the output of current rectifying and wave filtering circuit, input voltage and the reference voltage of described current rectifying and wave filtering circuit output are compared, if input voltage is less than reference voltage, represent that power input voltage is under-voltage, described comparison circuit output under-voltage protection control signal;
The switching circuit being connected with the output of described comparison circuit, according to the under-voltage protection control signal of described comparison circuit output, the output of control switch power supply chip stopcock power supply;
The sluggish loop being connected with described comparison circuit, controls described comparison circuit, deepens and accelerate the upset of comparison circuit; And
Respectively with the output of described current rectifying and wave filtering circuit, and the voltage stabilizing circuit that is connected of the power end of comparison circuit, switching circuit and sluggish loop;
Described comparison circuit comprises: parallel voltage-stabilizing diode A1 able to programme, capacitor C 2, the second bleeder circuit, capacitor C 3 that model is TL431;
Described the second bleeder circuit comprises resistance R 5, resistance R 6, resistance R 7, the resistance R 8 of series connection successively and the resistance R 9 being connected with the public connecting end of described resistance R 5 and described resistance R 6, the control utmost point of parallel voltage-stabilizing diode A1 able to programme described in the first termination of described resistance R 5, the output of a termination current rectifying and wave filtering circuit of described resistance R 8;
The anode of described parallel voltage-stabilizing diode A1 able to programme connects the power end of described comparison circuit by capacitor C 2, the negative electrode of described parallel voltage-stabilizing diode A1 able to programme connects the input of described switching circuit; The anode of parallel voltage-stabilizing diode A1 able to programme described in the first termination of described capacitor C 3, the second end of resistance R 5 described in the second termination of described capacitor C 3;
Described sluggish loop comprises resistance R 10, resistance R 11, the second triode Q2 and resistance R 12, the base stage of the second triode Q2 described in the first termination of described resistance R 10, the power end of sluggish loop described in the second termination of described resistance R 10, the base stage of the second triode Q2 described in the first termination of described resistance R 11, the second end ground connection of described resistance R 11, the collector electrode of the second triode Q2 described in the first termination of described resistance R 12, the second end ground connection of described resistance R 12; The collector electrode of described the second triode Q2 connects resistance R 9 described in described the second bleeder circuit.
2. under-voltage protecting circuit as claimed in claim 1; it is characterized in that; described voltage stabilizing circuit comprises the first switching tube and the first bleeder circuit; the output of current rectifying and wave filtering circuit described in the input termination of described the first switching tube; the power end of comparison circuit, switching circuit and sluggish loop described in the output termination of described the first switching tube; the output of current rectifying and wave filtering circuit described in the input termination of described the first bleeder circuit, the control end of the first switching tube described in the output termination of described the first bleeder circuit.
3. under-voltage protecting circuit as claimed in claim 2; it is characterized in that; described the first switching tube is the first triode; the collector electrode of described the first triode connects the output of described current rectifying and wave filtering circuit; the base stage of described the first triode connects the output of described current rectifying and wave filtering circuit by the first bleeder circuit, the emitter of described the first triode connects the power end of described comparison circuit, switching circuit and sluggish loop.
4. under-voltage protecting circuit as claimed in claim 1; it is characterized in that; described switching circuit comprises the 3rd switching tube and the 3rd bleeder circuit; the input of described the 3rd switching tube connects respectively the negative electrode of described parallel voltage-stabilizing diode A1 able to programme and the power end of switching circuit by the 3rd bleeder circuit, switching power source chip described in the output termination of described the 3rd switching tube.
5. under-voltage protecting circuit as claimed in claim 4; it is characterized in that; described the 3rd switching tube adopts MOSFET pipe; the grid of described MOSFET pipe connects respectively the negative electrode of described parallel voltage-stabilizing diode A1 able to programme and the power end of switching circuit by the 3rd bleeder circuit; the drain electrode of described MOSFET pipe connects described switching power source chip, the source ground of described MOSFET pipe.
6. a Switching Power Supply, it comprises current rectifying and wave filtering circuit and switching power source chip, it is characterized in that, described Switching Power Supply also comprises the under-voltage protecting circuit as described in claim 1-5 any one.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910189204.3A CN101752829B (en) | 2009-12-21 | 2009-12-21 | Undervoltage protection circuit and switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910189204.3A CN101752829B (en) | 2009-12-21 | 2009-12-21 | Undervoltage protection circuit and switching power supply |
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| Publication Number | Publication Date |
|---|---|
| CN101752829A CN101752829A (en) | 2010-06-23 |
| CN101752829B true CN101752829B (en) | 2014-06-25 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN200910189204.3A Active CN101752829B (en) | 2009-12-21 | 2009-12-21 | Undervoltage protection circuit and switching power supply |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101958527A (en) * | 2010-10-16 | 2011-01-26 | 深圳茂硕电源科技股份有限公司 | Boost type LED constant flow source under-voltage protection circuit |
| CN103746343B (en) * | 2013-12-13 | 2016-08-31 | 四川格来消防电器设备有限公司 | A kind of switching power circuit of fire-fighting emergency power supply |
| CN105186848B (en) * | 2015-10-16 | 2018-10-23 | 安科乐康（北京）诊断技术有限公司 | A kind of power protecting circuit and external defibrillator for external defibrillator |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1411012A (en) * | 2002-11-26 | 2003-04-16 | 莫红文 | Under voltage/subexcitation drop-away device circuit |
| CN2615942Y (en) * | 2003-01-27 | 2004-05-12 | 深圳市核达中远通电源技术有限公司 | Electric voltage protective circuit for AC/DC power source |
| JP3570141B2 (en) * | 1997-02-14 | 2004-09-29 | 富士ゼロックス株式会社 | Switching power supply |
| CN201247946Y (en) * | 2008-07-30 | 2009-05-27 | 深圳创维－Rgb电子有限公司 | Under-voltage protection circuit and switch power circuit |
| CN101471556A (en) * | 2007-12-25 | 2009-07-01 | 深圳Tcl新技术有限公司 | Under-voltage protection circuit |
-
2009
- 2009-12-21 CN CN200910189204.3A patent/CN101752829B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3570141B2 (en) * | 1997-02-14 | 2004-09-29 | 富士ゼロックス株式会社 | Switching power supply |
| CN1411012A (en) * | 2002-11-26 | 2003-04-16 | 莫红文 | Under voltage/subexcitation drop-away device circuit |
| CN2615942Y (en) * | 2003-01-27 | 2004-05-12 | 深圳市核达中远通电源技术有限公司 | Electric voltage protective circuit for AC/DC power source |
| CN101471556A (en) * | 2007-12-25 | 2009-07-01 | 深圳Tcl新技术有限公司 | Under-voltage protection circuit |
| CN201247946Y (en) * | 2008-07-30 | 2009-05-27 | 深圳创维－Rgb电子有限公司 | Under-voltage protection circuit and switch power circuit |
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| CN101752829A (en) | 2010-06-23 |
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