CN102035170B - PFC output overvoltage protection circuit - Google Patents
PFC output overvoltage protection circuit Download PDFInfo
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- CN102035170B CN102035170B CN 201110020461 CN201110020461A CN102035170B CN 102035170 B CN102035170 B CN 102035170B CN 201110020461 CN201110020461 CN 201110020461 CN 201110020461 A CN201110020461 A CN 201110020461A CN 102035170 B CN102035170 B CN 102035170B
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Abstract
The invention relates to a power factor correction (PFC) output overvoltage protection circuit, which comprises a PFC circuit, a first transistor, a second transistor, a first resistor, a second resistor, a third resistor, a TL431 and a voltage-regulator tube to form three parts, namely a PFC output overvoltage detection circuit, a positive feedback control circuit and an execution circuit so as to protect the abnormal rise of the PFC output voltage caused by short circuits of voltage feedback pins of a PFC-controlled integrated circuit (IC) and output pins of an error amplifier and the like. The circuit is simple and practical, and has high market value.
Description
Technical field
The present invention relates to the too high protective circuit of a kind of PFC output voltage.
Background technology
Voltage Feedback PIN and error amplification output PIN that at present a lot of PFC control IC are defined in adjacent pin position, and output voltage feedback PIN connects the end of oppisite phase of internal error amplifier, and its in-phase end connects an inner reference voltage source 2.5V.And the output voltage of error amplifier changes according to different loading between 1V to 6V.Load is lighter, and its output voltage is lower; Load is heavier, and its output voltage is higher.If the output PIN short circuit of Voltage Feedback PIN and error amplifier, the output voltage of error amplifier can be set at reference voltage 2.5V, no matter the load of PFC is light or heavy.And if be underloading at this moment, the output voltage of PFC can rise always, loses the control of voltage stabilizing, and the PFC output filter capacitor was lost efficacy because of overvoltage.
In addition, PIN is defined in adjacent pin position due to the output of Voltage Feedback PIN and error amplifier, if power supply in use, humidity due to environment, the reasons such as dust, and when causing Voltage Feedback sample resistance change in resistance, may cause that also the PFC output voltage raises extremely, thereby cause the PFC output filter capacitor to lose efficacy.
Summary of the invention
The purpose of this invention is to provide the too high protective circuit of a kind of PFC output voltage, realize that PFC controls the reasons such as the Voltage Feedback pin of IC and the short circuit of error amplifier output pin and causes the abnormal protection that raises of PFC output voltage.
The too high protective circuit of PFC output voltage of the present invention, comprise pfc circuit, the first transistor, transistor seconds, the first resistance, the second resistance, the 3rd resistance, TL431 and voltage-stabiliser tube, it is characterized in that: the feedback end (INV) of the control IC of described pfc circuit is connected with the collector electrode of described the first transistor, and the base stage of described the first transistor is connected with the positive pole of described voltage-stabiliser tube; The negative pole of described voltage-stabiliser tube is connected to the end of collector electrode, the second resistance one end and the 3rd resistance of reference voltage end, the transistor seconds of TL431; The emitter of described transistor seconds is connected to VCC, and the base stage of described transistor seconds is connected with the negative electrode of described TL431; Between described transistor seconds base stage and emitter and be connected to the first resistance; The other end of described the 3rd resistance and the grounded emitter of the first transistor; The other end of described the second resistance is connected with the output of described pfc circuit.
Overvoltage protection of the present invention loop is the process of a positive feedback; so as long as the PFC output voltage reaches the overvoltage protection point voltage that sets; this overvoltage crowbar will be pulled low to 0.3V to the feedback PIN voltage of PFC control IC rapidly, and the driver output of controlling IC turn-offs.After the too high trouble shooting of PFC output voltage, the supply power voltage that PFC controls IC need turn-off the protection that could remove this circuit and move, and circuit is simple, practical, has market value preferably.
Description of drawings
Fig. 1 is circuit connection diagram of the present invention.
Fig. 2 is the circuit diagram of one embodiment of the invention.
Embodiment
The present invention will be further described below in conjunction with drawings and Examples.
As shown in Figure 1, the invention provides the too high protective circuit of a kind of PFC output voltage, comprise pfc circuit, the first transistor Q954, transistor seconds Q955, the first resistance R 978, the second resistance R 926, the 3rd resistance R 927, TL431 and voltage-stabiliser tube ZD974, it is characterized in that: the feedback end (INV) of the control IC of described pfc circuit is connected with the collector electrode of described the first transistor Q954, and the base stage of described the first transistor Q954 is connected with the positive pole of described voltage-stabiliser tube ZD974; The negative pole of described voltage-stabiliser tube ZD974 is connected to the end of collector electrode, the second resistance R 926 1 ends and the 3rd resistance R 927 of reference voltage end, the transistor seconds Q955 of TL431; The emitter of described transistor seconds Q955 is connected to VCC, and the base stage of described transistor seconds Q955 is connected with the negative electrode of described TL431; Between described transistor seconds Q955 base stage and emitter and be connected to the first resistance R 978; The grounded emitter of the other end of described the 3rd resistance R 927 and the first transistor Q954; The other end of described the second resistance R 92 is connected with the output of described pfc circuit.
In order to allow those skilled in the art better understand the present invention; the below simply introduces circuit working principle of the present invention: please refer to Fig. 1 and Fig. 2; when causing for a certain reason the PFC output voltage extremely to raise; when reaching the over-voltage protection point of setting; pressure drop on resistance R 926 and R927 reaches 2.5V; the TL431 normal operation, its negative electrode flows to electric current.Along with the rising of PFC output voltage, the voltage on resistance R 926 and R927 is corresponding rising also, and the cathode voltage of TL431 descends, and flows to the also corresponding increase of electric current of the negative electrode of TL431, and also corresponding increase of the pressure drop that this electric current produces on R978.Q955 will begin conducting when the pressure drop on R978 surpasses 0.3V, the electric current that the C utmost point of Q955 flows out will arrive ground by R926 and R927, so the pressure drop on R926 and R927 also increases accordingly, thereby the electric current of the negative electrode that flows to TL431 is further increased, the electric current of this increase will produce larger pressure drop on R978, thereby make the further conducting of Q955, the electric current that its C utmost point flows out will further strengthen.This positive feedback will make the Q955 saturation conduction very soon, the ZD974 conducting, and the Q954 saturation conduction, the feedback PIN current potential of PFC being controlled IC is pulled low to 0.3V, and PFC controls the IC no-output.The PFC output voltage stops rising and begins and descends, and reaches the purpose of overvoltage protection.
The above is only preferred embodiment of the present invention, and all equalizations of doing according to the present patent application the scope of the claims change and modify, and all should belong to covering scope of the present invention.
Claims (1)
1. too high protective circuit of PFC output voltage, comprise pfc circuit, the first transistor, transistor seconds, the first resistance, the second resistance, the 3rd resistance, TL431 and voltage-stabiliser tube, it is characterized in that: the feedback end (INV) of the control IC of described pfc circuit is connected with the collector electrode of described the first transistor, and the base stage of described the first transistor is connected with the positive pole of described voltage-stabiliser tube; The negative pole of described voltage-stabiliser tube is connected to the end of collector electrode, the second resistance one end and the 3rd resistance of reference voltage end, the transistor seconds of TL431; The emitter of described transistor seconds is connected to VCC, and the base stage of described transistor seconds is connected with the negative electrode of described TL431; Between described transistor seconds base stage and emitter and be connected to the first resistance; The other end of described the 3rd resistance and the grounded emitter of the first transistor; The other end of described the second resistance is connected with the output of described pfc circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110020461 CN102035170B (en) | 2011-01-18 | 2011-01-18 | PFC output overvoltage protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110020461 CN102035170B (en) | 2011-01-18 | 2011-01-18 | PFC output overvoltage protection circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102035170A CN102035170A (en) | 2011-04-27 |
| CN102035170B true CN102035170B (en) | 2013-06-12 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201110020461 Expired - Fee Related CN102035170B (en) | 2011-01-18 | 2011-01-18 | PFC output overvoltage protection circuit |
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| CN (1) | CN102035170B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102497093A (en) | 2011-11-11 | 2012-06-13 | 无锡华润上华科技有限公司 | Output over-voltage protection circuit for power factor corrector |
| CN105449643B (en) * | 2014-08-28 | 2018-08-07 | 联想(北京)有限公司 | A kind of protection circuit and electronic equipment |
| CN106487101A (en) * | 2016-09-13 | 2017-03-08 | 中国农业大学 | A kind of current transformer energy taking device based on load control and method |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6222746B1 (en) * | 1998-02-09 | 2001-04-24 | Samsung Electronics Co., Ltd. | Power supply device and method with a power factor correction circuit |
| CN1667537A (en) * | 2004-03-08 | 2005-09-14 | 恩益禧电子股份有限公司 | Voltage regulator circuit having short-circuit protection circuit |
| CN201608638U (en) * | 2010-03-05 | 2010-10-13 | 福建捷联电子有限公司 | Fly-back power supply overpower compensation device inputted by wide voltage |
| CN201985507U (en) * | 2011-01-18 | 2011-09-21 | 福建捷联电子有限公司 | Overhigh output voltage protection circuit for power factor correction (PFC) |
-
2011
- 2011-01-18 CN CN 201110020461 patent/CN102035170B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6222746B1 (en) * | 1998-02-09 | 2001-04-24 | Samsung Electronics Co., Ltd. | Power supply device and method with a power factor correction circuit |
| CN1667537A (en) * | 2004-03-08 | 2005-09-14 | 恩益禧电子股份有限公司 | Voltage regulator circuit having short-circuit protection circuit |
| CN201608638U (en) * | 2010-03-05 | 2010-10-13 | 福建捷联电子有限公司 | Fly-back power supply overpower compensation device inputted by wide voltage |
| CN201985507U (en) * | 2011-01-18 | 2011-09-21 | 福建捷联电子有限公司 | Overhigh output voltage protection circuit for power factor correction (PFC) |
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| CN102035170A (en) | 2011-04-27 |
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