CN103795037A - Switching power supply protecting circuit and switching power supply including same - Google Patents
Switching power supply protecting circuit and switching power supply including same Download PDFInfo
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- CN103795037A CN103795037A CN201410022875.1A CN201410022875A CN103795037A CN 103795037 A CN103795037 A CN 103795037A CN 201410022875 A CN201410022875 A CN 201410022875A CN 103795037 A CN103795037 A CN 103795037A
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Abstract
The invention discloses a switching power supply protecting circuit and a switching power supply including the same. The switching power supply protecting circuit comprises a capacitor C1, a resistor R1, an audion Q1, a capacitor C2 and a resistor R2. After the capacitor C1 and the resistor R1 are in parallel connection, one end of the capacitor C1 is connected with the base electrode of the audion Q1 and the output end of an optocoupler Q2, and the other end of the capacitor C1 is connected with the emitting electrode of the audion Q1. One end of the capacitor C2 is connected with the emitting electrode of the audion Q1, and a node is connected with one end of the resistor R2 and a second pin of a current control type pulse width modulator Q3 after the other end of the capacitor C2 is connected with the collector electrode of the audion Q1. The other end of the resistor R2 is connected with an eighth pin of the current control type pulse width modulator Q3. According to the switching power supply protecting circuit and the switching power supply including the same, when the switching power supply is shut down, pulse width modulation output of the current control type pulse width modulator can be quickly closed, an MOS transistor is turned off, damage to the MOS transistor, a power resistor and the current control type pulse width modulator is avoided, the reliability of the entire switching power supply is improved, the structure is simple, and cost is low.
Description
Technical field
The present invention relates to switch power technology field, the Switching Power Supply that relates in particular to a kind of protective circuit of switch power source and comprise this protective circuit.
Background technology
Current-control type pulse modulation technology is a kind of technology of novelty, and it has overcome the shortcoming of conventional voltage control type pulse modulation technology, makes Switching Power Supply have the stability of transient response and height fast.In all kinds of current control mode pulse width modulator integrated chips of seeing in the market, the UC3842/3/4/5 series of Unitrode company of the U.S., external circuit wiring is simple, and element used is few, and superior performance is applied comparatively extensive.But, in Switching Power Supply design, select UC3842 chip as example take current control mode pulse width modulator, often ignore and closed input voltage moment, the operating state of UC3842 chip.Through in a large number Switching Power Supply being occurred to the analysis of damaged condition draws, in the time of switching off input voltage, duty ratio higher (reaching 98%) during due to the continuous reduction of input voltage and UC3842 chip operation, in order to maintain the state of output, the driving voltage duty ratio that causes UC3842 chip the 6th pin is increased, make metal oxide semiconductor field effect tube (metal-oxide-semiconductor) for a long time in conducting state, if now input voltage does not cut off, to cause metal-oxide-semiconductor, power resistor, even the permanent damage of UC3842 chip.
Summary of the invention
The object of the invention is to, by a kind of protective circuit of switch power source and the Switching Power Supply that comprises this protective circuit, solve the problem that above background technology part is mentioned.
For reaching this object, the present invention by the following technical solutions:
A kind of protective circuit of switch power source, comprises capacitor C 1, resistance R 1, triode Q1, capacitor C 2 and resistance R 2; Wherein, after capacitor C 1 is connected in parallel with resistance R 1, the output of optocoupler Q2 in the base stage of one end connecting triode Q1, Switching Power Supply, the emitter of other end connecting triode Q1; The emitter of one end connecting triode Q1 of capacitor C 2, the one end of node contact resistance R2 after the other end is connected with triode Q1 collector electrode, the second pin of current control mode pulse width modulator Q3, the other end of resistance R 2 connects the 8th pin of current control mode pulse width modulator Q3.
Especially, described triode Q1 selects NPN type triode.
The invention also discloses a kind of Switching Power Supply that comprises above-mentioned protective circuit of switch power source, comprising: capacitor C 1, resistance R 1, triode Q1, optocoupler Q2, resistance R 2, current control mode pulse width modulator Q3, resistance R 3, resistance R 4, capacitor C 3, diode D1 and inductance L 1; Wherein, after capacitor C 1 is connected in parallel with resistance R 1, the base stage of one end connecting triode Q1, the output of optocoupler Q2, the emitter of other end connecting triode Q1; The emitter of one end connecting triode Q1 of capacitor C 2, the one end of node contact resistance R2 after the other end is connected with triode Q1 collector electrode, the second pin of current control mode pulse width modulator Q3, node after the other end of resistance R 2 is connected with resistance R 3 one end connects the 8th pin of current control mode pulse width modulator Q3, and the other end of resistance R 3 connects the output of optocoupler Q2; Node after one end of resistance R 4 is connected with one end of capacitor C 3 connects the 7th pin of current control mode pulse width modulator Q3, the other end connects one end of diode D1, the other end of diode D1 connects one end of inductance L 1, the emitter of the node connecting triode Q1 after the other end of inductance L 1 is connected with the other end of capacitor C 3, the 5th pin of current control mode pulse width modulator Q3.
Especially, described triode Q1 selects NPN type triode.
The protective circuit of switch power source that the present invention proposes and the Switching Power Supply that comprises this protective circuit can be in the time that Switching Power Supply be shut down; the pulse-width modulation of close current control type pulse width modulator (as UC3842 chip) output rapidly; turn-off metal-oxide-semiconductor; thereby avoid the damage of metal-oxide-semiconductor, power resistor, current control mode pulse width modulator; improved the reliability of whole Switching Power Supply, and this protective circuit of switch power source is simple in structure, cost is low.
Accompanying drawing explanation
The switching power circuit structure chart that comprises protective circuit of switch power source that Fig. 1 provides for the embodiment of the present invention.
Embodiment
Below in conjunction with drawings and Examples, the invention will be further described.Be understandable that, specific embodiment described herein is only for explaining the present invention, but not limitation of the invention.It also should be noted that, for convenience of description, in accompanying drawing, only show part related to the present invention but not full content.
As shown in Figure 1, the switching power circuit structure chart that comprises protective circuit of switch power source that Fig. 1 provides for the embodiment of the present invention.
Embodiment mono-
In the present embodiment, protective circuit of switch power source specifically comprises capacitor C 1, resistance R 1, triode Q1, capacitor C 2 and resistance R 2.
Wherein, after capacitor C 1 is connected in parallel with resistance R 1, the output of optocoupler Q2 in the base stage of one end connecting triode Q1, Switching Power Supply, the emitter of other end connecting triode Q1; The emitter of one end connecting triode Q1 of capacitor C 2, the one end of node contact resistance R2 after the other end is connected with triode Q1 collector electrode, the second pin of current control mode pulse width modulator Q3, the other end of resistance R 2 connects the 8th pin of current control mode pulse width modulator Q3.
In the present embodiment, described triode Q1 selects NPN type triode.Described current control mode pulse width modulator Q3 can select any of UC3842/3/4/5 family chip, preferably UC3842 chip.
Embodiment bis-
The Switching Power Supply that comprises above-mentioned protective circuit of switch power source in the present embodiment comprises: capacitor C 1, resistance R 1, triode Q1, optocoupler Q2, resistance R 2, current control mode pulse width modulator Q3, resistance R 3, resistance R 4, capacitor C 3, diode D1 and inductance L 1.
Wherein, after capacitor C 1 is connected in parallel with resistance R 1, the base stage of one end connecting triode Q1, the output of optocoupler Q2, the emitter of other end connecting triode Q1; The emitter of one end connecting triode Q1 of capacitor C 2, the one end of node contact resistance R2 after the other end is connected with triode Q1 collector electrode, the second pin of current control mode pulse width modulator Q3, node after the other end of resistance R 2 is connected with resistance R 3 one end connects the 8th pin of current control mode pulse width modulator Q3, and the other end of resistance R 3 connects the output of optocoupler Q2; Node after one end of resistance R 4 is connected with one end of capacitor C 3 connects the 7th pin of current control mode pulse width modulator Q3, the other end connects one end of diode D1, the other end of diode D1 connects one end of inductance L 1, the emitter of the node connecting triode Q1 after the other end of inductance L 1 is connected with the other end of capacitor C 3, the 5th pin of current control mode pulse width modulator Q3.
In the present embodiment, described triode Q1 selects NPN type triode.Described current control mode pulse width modulator Q3 can select any of UC3842/3/4/5 family chip, preferably UC3842 chip.
Select UC3842 chip as example take current control mode pulse width modulator Q3 below, the course of work of the Switching Power Supply that comprises above-mentioned protective circuit of switch power source is described.
When work, by resistance R 2, capacitor C 2 is charged, raise the voltage of UC3842 chip the second pin (comparator negative terminal), thereby in the time that Switching Power Supply is closed, close rapidly the pulse-width modulation output of UC3842 chip, turn-off metal-oxide-semiconductor, avoided the damage of metal-oxide-semiconductor, power resistor.It should be noted that, the size of resistance R 2 and capacitor C 2 need meet in actual applications: in the time that Switching Power Supply is worked, the voltage of UC3842 chip the second pin is not higher than the voltage of its first pin, in the time that Switching Power Supply is shut down, can trigger again, close rapidly the pulse-width modulation output of UC3842 chip.
Technical scheme of the present invention can be in the time that Switching Power Supply be shut down; the pulse-width modulation of close current control type pulse width modulator output rapidly; turn-off metal-oxide-semiconductor; avoid the damage of metal-oxide-semiconductor, power resistor, current control mode pulse width modulator; improved the reliability of whole Switching Power Supply, and this protective circuit of switch power source is simple in structure, cost is low.
Note, above are only preferred embodiment of the present invention and institute's application technology principle.Skilled person in the art will appreciate that and the invention is not restricted to specific embodiment described here, can carry out for a person skilled in the art various obvious variations, readjust and substitute and can not depart from protection scope of the present invention.Therefore, although the present invention is described in further detail by above embodiment, the present invention is not limited only to above embodiment, in the situation that not departing from the present invention's design, can also comprise more other equivalent embodiment, and scope of the present invention is determined by appended claim scope.
Claims (4)
1. a protective circuit of switch power source, is characterized in that, comprises capacitor C 1, resistance R 1, triode Q1, capacitor C 2 and resistance R 2; Wherein, after capacitor C 1 is connected in parallel with resistance R 1, the output of optocoupler Q2 in the base stage of one end connecting triode Q1, Switching Power Supply, the emitter of other end connecting triode Q1; The emitter of one end connecting triode Q1 of capacitor C 2, the one end of node contact resistance R2 after the other end is connected with triode Q1 collector electrode, the second pin of current control mode pulse width modulator Q3, the other end of resistance R 2 connects the 8th pin of current control mode pulse width modulator Q3.
2. protective circuit of switch power source according to claim 1, is characterized in that, described triode Q1 selects NPN type triode.
3. a Switching Power Supply that comprises protective circuit of switch power source described in claim 1, comprising: capacitor C 1, resistance R 1, triode Q1, optocoupler Q2, resistance R 2, current control mode pulse width modulator Q3, resistance R 3, resistance R 4, capacitor C 3, diode D1 and inductance L 1; Wherein, after capacitor C 1 is connected in parallel with resistance R 1, the base stage of one end connecting triode Q1, the output of optocoupler Q2, the emitter of other end connecting triode Q1; The emitter of one end connecting triode Q1 of capacitor C 2, the one end of node contact resistance R2 after the other end is connected with triode Q1 collector electrode, the second pin of current control mode pulse width modulator Q3, node after the other end of resistance R 2 is connected with resistance R 3 one end connects the 8th pin of current control mode pulse width modulator Q3, and the other end of resistance R 3 connects the output of optocoupler Q2; Node after one end of resistance R 4 is connected with one end of capacitor C 3 connects the 7th pin of current control mode pulse width modulator Q3, the other end connects one end of diode D1, the other end of diode D1 connects one end of inductance L 1, the emitter of the node connecting triode Q1 after the other end of inductance L 1 is connected with the other end of capacitor C 3, the 5th pin of current control mode pulse width modulator Q3.
4. the Switching Power Supply that comprises protective circuit of switch power source according to claim 3, is characterized in that, described triode Q1 selects NPN type triode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410022875.1A CN103795037A (en) | 2014-01-17 | 2014-01-17 | Switching power supply protecting circuit and switching power supply including same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410022875.1A CN103795037A (en) | 2014-01-17 | 2014-01-17 | Switching power supply protecting circuit and switching power supply including same |
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| CN103795037A true CN103795037A (en) | 2014-05-14 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201410022875.1A Pending CN103795037A (en) | 2014-01-17 | 2014-01-17 | Switching power supply protecting circuit and switching power supply including same |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105656463A (en) * | 2016-04-05 | 2016-06-08 | 深圳市莱福德光电有限公司 | Protection circuit applied to super junction MOS (metal oxide semiconductor) |
| CN107359793A (en) * | 2017-08-22 | 2017-11-17 | 姚静洁 | A kind of direct-current switch power supply circuit |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2730022Y (en) * | 2004-09-15 | 2005-09-28 | 徐晓宁 | Automatic recovery protection circuit type switch supply unit |
| CN101478241A (en) * | 2008-01-02 | 2009-07-08 | 檀明升 | Method and circuit for reducing idle loss of switch power supply |
| US20120014142A1 (en) * | 2010-07-19 | 2012-01-19 | Welland Industrial Co., Ltd. | Power conversion apparatus for correcting power factor |
-
2014
- 2014-01-17 CN CN201410022875.1A patent/CN103795037A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2730022Y (en) * | 2004-09-15 | 2005-09-28 | 徐晓宁 | Automatic recovery protection circuit type switch supply unit |
| CN101478241A (en) * | 2008-01-02 | 2009-07-08 | 檀明升 | Method and circuit for reducing idle loss of switch power supply |
| US20120014142A1 (en) * | 2010-07-19 | 2012-01-19 | Welland Industrial Co., Ltd. | Power conversion apparatus for correcting power factor |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105656463A (en) * | 2016-04-05 | 2016-06-08 | 深圳市莱福德光电有限公司 | Protection circuit applied to super junction MOS (metal oxide semiconductor) |
| CN105656463B (en) * | 2016-04-05 | 2023-08-15 | 深圳市莱福德光电有限公司 | Protection circuit for super-junction MOS application |
| CN107359793A (en) * | 2017-08-22 | 2017-11-17 | 姚静洁 | A kind of direct-current switch power supply circuit |
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Application publication date: 20140514 |