CN101752829A - Undervoltage protection circuit and switching power supply - Google Patents
Undervoltage protection circuit and switching power supply Download PDFInfo
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- CN101752829A CN101752829A CN 200910189204 CN200910189204A CN101752829A CN 101752829 A CN101752829 A CN 101752829A CN 200910189204 CN200910189204 CN 200910189204 CN 200910189204 A CN200910189204 A CN 200910189204A CN 101752829 A CN101752829 A CN 101752829A
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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, advantage such as efficient, Switching Power Supply has been widely used in various electric equipment products.In the middle of practical application, generally require Switching Power Supply that under-voltage protection function is arranged.
The realization of under-voltage protection function generally is to be realized by the switching power source chip of special use.But this chip generally all is the input of wide power voltage; as 85～265VAC; and in some application scenario, as the emergency lighting occasion, require when being not less than 0.6 times of rated supply voltage and not being 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 not enough only depending on chip itself to carry out under-voltage protection, must add control circuit.
For above-mentioned application, the under-voltage protecting circuit of this respect has been arranged also.But in these circuit, all be at first to produce the required direct voltage of circuit by transformer coupled, rectifying and wave-filtering, pass through the variation of comparison circuit monitoring power voltage again, the conducting of the height control switch pipe of amplifier output level or the adhesive of relay, and then the break-make of control switching.These circuit are because of having increased transformer or Transformer Winding, and output circuit has increased relay or switching tube, thereby increased the size of wiring board and the power consumption of entire circuit, reduced the reliability of circuit.
Summary of the invention
The purpose of the embodiment of the invention is to provide a kind of under-voltage protecting circuit, is intended to solve the problem that there is the big and poor reliability of power consumption in existing under-voltage protecting circuit.
The embodiment of the invention is achieved in that a kind of under-voltage protecting circuit, and described circuit comprises:
The comparison circuit that is connected with the output of current rectifying and wave filtering circuit, the 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, the expression power input voltage is under-voltage, described comparison circuit output under-voltage protection control signal;
The switching circuit that is connected with the output of described comparison circuit is according to the under-voltage protection control signal of described comparison circuit output, the output of control switching chip stopcock power supply;
The sluggish loop that is connected with described comparison circuit is controlled described comparison circuit, deepens and quicken 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.
Another purpose of the embodiment of the 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 behind the Switching Power Supply input AC electric rectification; need not to come power taking to press by increasing transformer or increasing the winding that has transformer; save the space of wiring board; also reduce the power consumption of entire circuit; in addition; this under-voltage protecting circuit is the output by control switching chip stopcock power supply; avoided realizing break-make at the output increase switching tube or the relay of Switching Power Supply; reduced power consumption; save the space, improved reliability.
Description of drawings
Fig. 1 is the structure chart of the switch power supply under-voltage protecting circuit that provides of the embodiment of the invention;
Fig. 2 is the exemplary circuit figure of the switch power supply under-voltage protecting circuit that provides of the embodiment of the invention.
Embodiment
In order to make purpose of the present invention, technical scheme and advantage clearer,, the present invention is further elaborated below in conjunction with drawings and Examples.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.
Fig. 1 shows the structure of the switch power supply under-voltage protecting circuit that the embodiment of the invention provides, and for convenience of explanation, only shows the part relevant with the embodiment of the 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 that is connected with the output of current rectifying and wave filtering circuit, the switching circuit 400 that is connected with the output of comparison circuit 300, the sluggish loop 200 that is 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 the power end of comparison circuit 300, switching circuit 400 and sluggish loop 200.
200 pairs of comparisons of sluggish loop circuit 300 is controlled, and deepens and quicken 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 invention provides, and for convenience of explanation, only shows the part relevant with the embodiment of the invention.
As one embodiment of the invention, 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 first bleeder circuit 102, wherein, 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 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, 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 that is 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 a 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, 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 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 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 the output of comparator 301 and the power end VCC of switching circuit 400 respectively 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, first end of second end difference connecting resistance R14 of resistance R 13 and the grid of MOSFET pipe Q3, the second end ground connection of resistance R 14.
Its operation principle is:
When the Switching Power Supply AC-input voltage reduces; comparison circuit 300 compares the input voltage and the reference voltage of current rectifying and wave filtering circuit output; if input voltage is less than reference voltage; the expression AC-input voltage is under-voltage; comparison circuit 300 output under-voltage protection control signals; switching circuit 400 is according to the under-voltage protection control signal of comparison circuit 300 output, the output of control switching 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 behind the Switching Power Supply input AC electric rectification; need not to come power taking to press by increasing transformer or increasing the winding that has transformer; save the space of wiring board; also reduce the power consumption of entire circuit; in addition; this under-voltage protecting circuit is the output by control switching chip stopcock power supply; avoided realizing break-make at the output increase switching tube or the relay of Switching Power Supply; reduced power consumption; save the space, improved reliability.
The above only is preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of being done within the spirit and principles in the present invention, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. a under-voltage protecting circuit is characterized in that, described circuit comprises:
The comparison circuit that is connected with the output of current rectifying and wave filtering circuit, the 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, the expression power input voltage is under-voltage, described comparison circuit output under-voltage protection control signal;
The switching circuit that is connected with the output of described comparison circuit is according to the under-voltage protection control signal of described comparison circuit output, the output of control switching chip stopcock power supply;
The sluggish loop that is connected with described comparison circuit is controlled described comparison circuit, deepens and quicken 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.
2. under-voltage protecting circuit as claimed in claim 1; it is characterized in that; described voltage stabilizing circuit comprises first switching tube and first bleeder circuit; the output of the described current rectifying and wave filtering circuit of input termination of described first switching tube; described first output end of switching tube connects the power end of described comparison circuit, switching circuit and sluggish loop; the output of the described current rectifying and wave filtering circuit of input termination of described first bleeder circuit, described first control end of switching tube of the output termination of described first bleeder circuit.
3. under-voltage protecting circuit as claimed in claim 2; it is characterized in that; described first switching tube is first triode; the collector electrode of described first triode connects the output of described current rectifying and wave filtering circuit; the base stage of described first triode connects the output of described current rectifying and wave filtering circuit by first bleeder circuit, and the emitter of described first triode connects the power end of described comparison circuit, switching circuit and sluggish loop.
4. under-voltage protecting circuit as claimed in claim 2; it is characterized in that; described comparison circuit comprises comparator, second bleeder circuit and electric capacity; the Input voltage terminal of described comparator connects the output of described current rectifying and wave filtering circuit by second bleeder circuit; the reference voltage end of described comparator connects the power end of described comparison circuit, the input of the described switching circuit of output termination of described comparator by electric capacity.
5. under-voltage protecting circuit as claimed in claim 4; it is characterized in that; described comparator adopts parallel voltage-stabilizing diode able to programme; the control utmost point of described parallel voltage-stabilizing diode able to programme connects the output of described current rectifying and wave filtering circuit by second bleeder circuit; the anode of described parallel voltage-stabilizing diode able to programme connects the power end of described comparison circuit by electric capacity, and the negative electrode of described parallel voltage-stabilizing diode able to programme connects the input of described switching circuit.
6. under-voltage protecting circuit as claimed in claim 4; it is characterized in that; described sluggish loop comprises the second switch pipe, the power end of the described sluggish loop of input termination of described second switch pipe, second bleeder circuit of the described comparison circuit of output termination of described second switch pipe.
7. under-voltage protecting circuit as claimed in claim 6; it is characterized in that; described second switch pipe is second triode; the base stage of described second triode connects the power end of described sluggish loop; the collector electrode of described second triode connects second bleeder circuit of described comparison circuit, the grounded emitter of described second triode.
8. under-voltage protecting circuit as claimed in claim 4; 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 the output of comparator and the power end of switching circuit respectively by the 3rd bleeder circuit, and described the 3rd output end of switching tube connects described switching power source chip.
9. under-voltage protecting circuit as claimed in claim 8; it is characterized in that; described the 3rd switching tube adopts the MOSFET pipe; the grid of described MOSFET pipe connects the output of comparator and the power end of switching circuit respectively 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.
10. 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 each described under-voltage protecting circuit as claim 1-9.
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 true CN101752829A (en) | 2010-06-23 |
| CN101752829B 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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| CN (1) | CN101752829B (en) |
Cited By (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 |
| CN103746343A (en) * | 2013-12-13 | 2014-04-23 | 四川格来消防电器设备有限公司 | Switching power supply circuit of firefighting emergency power supply |
| CN105186848A (en) * | 2015-10-16 | 2015-12-23 | 安科乐康（北京）诊断技术有限公司 | External defibrillator power supply protection circuit and external defibrillator |
Family Cites Families (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 |
| CN1206679C (en) * | 2002-11-26 | 2005-06-15 | 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 |
| CN101471556B (en) * | 2007-12-25 | 2012-01-11 | 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 |
-
2009
- 2009-12-21 CN CN200910189204.3A patent/CN101752829B/en active Active
Cited By (5)
| 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 |
| CN103746343A (en) * | 2013-12-13 | 2014-04-23 | 四川格来消防电器设备有限公司 | Switching power supply circuit of firefighting emergency power supply |
| 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 |
| CN105186848A (en) * | 2015-10-16 | 2015-12-23 | 安科乐康（北京）诊断技术有限公司 | External defibrillator power supply protection circuit and external defibrillator |
| 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 |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101752829B (en) | 2014-06-25 |
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