CN104253546B - A kind of switching power circuit - Google Patents
A kind of switching power circuit Download PDFInfo
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- CN104253546B CN104253546B CN201410492046.XA CN201410492046A CN104253546B CN 104253546 B CN104253546 B CN 104253546B CN 201410492046 A CN201410492046 A CN 201410492046A CN 104253546 B CN104253546 B CN 104253546B
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Abstract
The invention discloses a kind of switching power circuit, wherein, first outfan of current rectifying and wave filtering circuit passes sequentially through the negative electrode of the first resistance and the second resistance and the second diode and connects, the anode of the second diode is connected to ground, first end of the primary coil of transformator is connected with the first outfan of current rectifying and wave filtering circuit, second end of the primary coil of transformator passes sequentially through the first MOS switch pipe, second MOS switch pipe is connected to ground, the base stage of the first MOS switch pipe and the common port of the first resistance and the second resistance connect, the negative electrode of the first diode and anode are connected with base stage and the source electrode of the first MOS switch pipe respectively, the input of pwm control circuit and outfan are connected with the outfan of secondary coil and the base stage of the second MOS switch pipe of transformator respectively, second outfan of current rectifying and wave filtering circuit is connected to ground.
Description
[technical field]
The present invention relates to a kind of switching power circuit.
[background technology]
At present, in the switching power circuit of high voltage input, MOSFET is easily damaged.Additionally when powering on start,
Easily there is spike, or the temporary voltage beyond rated output voltage in the voltage of outfan, and electrical equipment exists impaired
Risk.
[summary of the invention]
In order to overcome the deficiencies in the prior art, the invention provides a kind of switching power circuit, damaged reducing MOSFET
Bad probability；Further, the peak voltage occurred when reducing or reduce start.
A kind of switching power circuit, including current rectifying and wave filtering circuit, pwm control circuit and transformator, also include the first resistance,
Second resistance, the first MOS switch pipe, the second MOS switch pipe, the first diode and the second diode, described rectification
First outfan of filter circuit passes sequentially through the negative electrode of described first resistance and the second resistance and the second diode and connects,
The anode of described second diode is connected to ground, the first end of the primary coil of described transformator and described rectifying and wave-filtering electricity
First outfan on road connects, the second end of the primary coil of described transformator pass sequentially through the first MOS switch pipe, the
Two MOS switch pipes are connected to ground, the base stage of described first MOS switch pipe and the first resistance and the common port of the second resistance
Connecting, the negative electrode of described first diode and anode are connected with base stage and the source electrode of the first MOS switch pipe respectively, described
The input of pwm control circuit and outfan respectively with outfan and the second MOS switch pipe of the secondary coil of transformator
Base stage connect, the second outfan of described current rectifying and wave filtering circuit is connected to ground, described pwm control circuit be used for basis
The break-make of the second MOS switch pipe described in the Control of Voltage of described transformer secondary coil outfan.
Preferably, also include at the beginning of the 3rd resistance, the 4th resistance, the first electric capacity and the 3rd diode, described transformator
First end of level coil passes sequentially through the negative electrode of the first electric capacity, the 4th resistance and the 3rd diode and connects, and the described 3rd 2
The anode of pole pipe is connected with the second end of the primary coil of described transformator, and the two ends of described 3rd resistance are respectively with described
The two ends of the first electric capacity connect.
Preferably, also include the 4th diode, described pwm control circuit also include the 5th resistance, the 6th resistance,
Seven resistance, the 8th resistance, the 9th resistance, the 6th electric capacity, controllable accurate source of stable pressure, optocoupler and power drives chip,
First end of the secondary coil of described transformator is connected with the anode of described 4th diode, the moon of described 4th diode
Pole passes sequentially through the 6th resistance and the 5th resistance eutral grounding, and the negative electrode of described 4th diode passes through described 8th resistance and light
The anode of coupling input connects, the negative electrode of described controllable accurate source of stable pressure and anode respectively with the moon of described optocoupler input
Pole and ground connect, and the reference pole of described controllable accurate source of stable pressure is connected with the common port of described 5th resistance and the 6th resistance,
The negative electrode of described controllable accurate source of stable pressure is connected with the anode of described optocoupler input by described 7th resistance, described can
The negative electrode of control precision voltage regulator passes sequentially through the public of the 6th electric capacity and the 9th resistance and described 5th resistance and the 6th resistance
End connects, the colelctor electrode of the outfan of described optocoupler and emitter-base bandgap grading respectively with the feedback end of described power drives chip and ground company
Connect, when the feedback end of described power drives chip is described second MOS switch pipe cut-off under low level state, work as institute
Under the state that the feedback end stating power drives chip is high level described 2nd MOS open the light pipe base stage and pwm signal even
Connect.
Preferably, also include the 3rd electric capacity, the two ends of described 3rd electric capacity respectively with negative electrode and the transformation of the 4th diode
Second end of device secondary coil connects.
Preferably, described pwm control circuit also includes the 7th electric capacity, and the negative electrode of described optocoupler input is by described the
Seven electric capacity are connected to ground.
Preferably, also include the second electric capacity, the first end of the primary coil of described transformator by described second electric capacity with
Ground connects.
Preferably, described controllable accurate source of stable pressure is TL431 controllable accurate source of stable pressure.
Preferably, described power drives chip is the NCP1075 power drives chip comprising described second MOS switch pipe
Or NCP1072 power drives chip.
By using two MOS switch pipes and accessory circuit thereof, effectively prevent when the overtension of input, MOS
The situation that switching tube is damaged；It addition, the spike occurred when can effectively reduce start by increase the 7th resistance
Voltage.
[accompanying drawing explanation]
Fig. 1 is the circuit diagram of the switching power circuit of an embodiment of the present invention；
Fig. 2 is the circuit theory diagrams of the switching power circuit of another kind embodiment of the present invention.
[detailed description of the invention]
Preferred embodiment to invention is described in further detail below.
As illustrated in fig. 1 and 2, the switching power circuit of a kind of embodiment, including current rectifying and wave filtering circuit, pwm control circuit,
Transformator T, the first resistance R1, the second resistance R2, the first MOS switch pipe Q1, the second MOS switch pipe Q2, first
Diode D1 and the second diode D2, the first outfan of described current rectifying and wave filtering circuit passes sequentially through described first resistance
The negative electrode of R1 and the second resistance R2 and the second diode D2 connects, and the anode of described second diode D2 is connected to ground,
First end of the primary coil of described transformator T is connected with the first outfan of described current rectifying and wave filtering circuit, described transformation
Second end of the primary coil of device passes sequentially through the first MOS switch pipe Q1, the second MOS switch pipe Q2 is connected to ground, institute
The common port of the base stage and the first resistance R1 and the second resistance R2 of stating the first MOS switch pipe Q1 connects, and the described 1st
The negative electrode of pole pipe D1 and anode are connected with base stage and the source electrode of the first MOS switch pipe Q1 respectively, and described PWM controls electricity
The input on road and outfan respectively with outfan and the base stage of the second MOS switch pipe Q2 of the secondary coil of transformator T
Connecting, the second outfan of described current rectifying and wave filtering circuit is connected to ground, and described pwm control circuit is for according to described change
The break-make of the second MOS switch pipe Q2 described in the Control of Voltage of depressor T secondary coil outfan.
When pwm control circuit detects the overtension of transformator T secondary coil outfan, control the 2nd MOS and open
Pass pipe turns off, and when pwm control circuit detects the brownout of transformator T secondary coil outfan, then controls the
Two MOS switch pipe conductings, such that it is able to maintain the voltage of transformator T secondary coil outfan to keep stable.
Preferably, also include the 3rd resistance R3, the 4th resistance R4, the first electric capacity C1 and the 3rd diode D3, described
First end of the primary coil of transformator T passes sequentially through the first electric capacity C1, the 4th resistance R4 and the 3rd diode D3
Negative electrode connects, and the anode of described 3rd diode D3 is connected with the second end of the primary coil of described transformator T, described
Two ends with described first electric capacity C1 respectively, the two ends of the 3rd resistance R3 are connected.
Preferably, also include that the 4th diode D4, described pwm control circuit also include the 5th resistance R5, the 6th resistance
R6, the 7th resistance R7, the 8th resistance R8, the 9th resistance R9, the 6th electric capacity C6, controllable accurate source of stable pressure U3, light
Coupling U2, power drives chip U1 and the 7th electric capacity C7, described controllable accurate source of stable pressure is TL431 controllable accurate voltage stabilizing
Source, described power drives chip U1 is the NCP1075 power drives chip comprising described second MOS switch pipe Q1,
First end of the secondary coil of described transformator T is connected with the anode of described 4th diode D4, described 4th diode
The negative electrode of D4 passes sequentially through the 6th resistance R6 and the 5th resistance R5 ground connection, and the negative electrode of described 4th diode D4 passes through institute
Stating the 8th resistance R8 to be connected with the anode of optocoupler U2 input, negative electrode and the anode of described controllable accurate source of stable pressure U3 divide
Not with the negative electrode of described optocoupler U2 input and be connected, the reference pole of described controllable accurate source of stable pressure U3 and described the
The common port of five resistance R5 and the 6th resistance R6 connects, and the negative electrode of described controllable accurate source of stable pressure U3 passes through the described 7th
Resistance R7 is connected with the anode of described optocoupler U2 input, and the negative electrode of described controllable accurate source of stable pressure U3 passes sequentially through
The common port of six electric capacity C6 and the 9th resistance R9 and described 5th resistance R5 and the 6th resistance R6 is connected, described optocoupler
The colelctor electrode of the outfan of U2 and emitter-base bandgap grading are connected with power end and the ground of described power drives chip U1 respectively, described optocoupler
The negative electrode of U2 input is connected to ground by described 7th electric capacity C7.
Preferably, also including the second electric capacity C2 and the 3rd electric capacity C3, the first end of the primary coil of described transformator T leads to
Cross described second electric capacity C2 to be connected to ground, the two ends of described 3rd electric capacity C3 respectively with the negative electrode of the 4th diode D4 and
Second end of transformator T secondary coil connects.6th resistance R6 can be by the 14th resistance R14 and outfan OUT
Connect.
When the voltage of transformator T secondary coil output is through the rectification of the 4th diode D4 and the filtering of the 3rd electric capacity C3
After, the voltage of outfan OUT is through the 14th resistance R14, the 6th resistance R6 and the dividing potential drop of the 5th resistance R5, controlled
The voltage of the reference pole input of precision voltage regulator U3 is the voltage of the 5th resistance R5, due to controllable accurate source of stable pressure U3
The reference voltage of reference pole be 2.5V, if the voltage of the 5th resistance R5 is more than 2.5V, controllable accurate source of stable pressure
U3 turns on, and electric current flows through the input of optocoupler U2, thus the outfan of optocoupler U2 turns on, power drives chip U1
Feedback end FB be low level, thus the second MOS switch pipe Q2 cannot receive pwm signal and end, then,
Do not have electric current to flow through from the primary coil of transformator T, cause the voltage of outfan OUT to decline, until the 5th resistance R5
Voltage less than 2.5V, the feedback end FB of power drives chip U1 be high level, to second MOS switch pipe Q2 provide
Pwm signal, the primary coil of transformator T has electric current to flow through, so constantly circulation, thus ensure that outfan OUT
Voltage stabilization.
When whole electric current just starts power up work, when the voltage of the 5th resistance R5, more than 2.5V, controllable accurate is steady
During potential source U3 conducting, at this time optocoupler U2 does not has enough time to turn on, therefore, it is possible to outfan OUT can be caused
There is the voltage exceeding rated output voltage of moment in voltage, by arranging the 7th resistance R7, even if optocoupler U2 does not comes
And conducting, the voltage of outfan OUT through the 8th resistance R8, the 7th resistance R7 and controllable accurate source of stable pressure U3,
Such that it is able to shunting one part of current, to reduce the electric current flowing through the 5th resistance R5, such that it is able to reduce outfan OUT
Voltage.
It addition, during start, the voltage of outfan OUT can also be through the 8th resistance R8, the 7th resistance R7 to the 6th electricity
Capacity charge, to absorb a part of voltage, thus the spike of outfan OUT when can also absorb start.
Preferably, the first resistance R1 can pass sequentially through the 11st resistance R11 and R12, the first of current rectifying and wave filtering circuit
End voltage may be up to 800VDC, during work by the first resistance R1, the 11st resistance R11, the 12nd resistance R12,
Second resistance R2 and the second diode D2 composition bleeder circuit powers to the base stage of the first MOS switch pipe Q1, and the one or two
Pole pipe D1 is that Zener diode makes to be controlled by the pressure reduction between base stage and the source electrode of the first MOS switch pipe Q1 during its work
At about 20V.When the second MOS switch pipe Q2 closes, although the base stage of the first MOS switch pipe Q1 has dividing potential drop,
But because of the second MOS switch pipe Q2 cut-off, so the first MOS switch pipe Q1 cannot work；When the second MOS switch pipe
During Q2 conducting, the base stage of the first MOS switch pipe Q1 is owing to there being bias voltage to turn on, although at this moment the first MOS switch
The drain electrode of pipe Q1 voltage over the ground measures about 1000V, but connects with the second MOS switch pipe Q2 because of it, institute
The voltage divided with the first MOS switch pipe Q1 is about at about 500V, in the tolerance range of common MOS switch pipe,
Therefore, it can choose the second MOS switch pipe Q2 that pressure voltage is about 600V.
When second MOS switch pipe Q2 cut-off time, the second end of the primary coil of transformator T by the 3rd diode D3,
4th resistance R4 is charged to the first electric capacity C1, and when the second MOS switch pipe Q2 conducting, the first electric capacity C1 leads to
Cross the 3rd resistance R3 and the 13rd resistance R13 to discharge, to ensure the normal work of transformator T.
Above content is to combine concrete preferred implementation further description made for the present invention, it is impossible to assert
Being embodied as of the present invention is confined to these explanations.For general technical staff of the technical field of the invention,
Without departing from the inventive concept of the premise, it is also possible to make some simple deduction or replace, should be all considered as belonging to this
The scope of patent protection that invention is determined by the claims submitted to.
Claims (7)
1. a switching power circuit, including current rectifying and wave filtering circuit, pwm control circuit and transformator, is characterized in that,
Also include the first resistance, the second resistance, the first MOS switch pipe, the second MOS switch pipe, the first diode and second
Diode, the first outfan of described current rectifying and wave filtering circuit passes sequentially through described first resistance and the second resistance and the two or two
The negative electrode of pole pipe connects, and the anode of described second diode is connected to ground, the first end of the primary coil of described transformator
Being connected with the first outfan of described current rectifying and wave filtering circuit, the second end of the primary coil of described transformator passes sequentially through
One MOS switch pipe, the second MOS switch pipe are connected to ground, the base stage of described first MOS switch pipe and the first resistance with
The common port of the second resistance connects, the negative electrode of described first diode and anode respectively with the base stage of the first MOS switch pipe
Connect with source electrode, the input of described pwm control circuit and outfan respectively with the outfan of the secondary coil of transformator
Connecting with the base stage of the second MOS switch pipe, the second outfan of described current rectifying and wave filtering circuit is connected to ground, described PWM
Control circuit is for leading to according to the second MOS switch pipe described in the Control of Voltage of the secondary coil outfan of described transformator
Disconnected；
Also include the 4th diode, described pwm control circuit also include the 5th resistance, the 6th resistance, the 7th resistance,
8th resistance, the 9th resistance, the 6th electric capacity, controllable accurate source of stable pressure, optocoupler and power drives chip, described transformation
First end of the secondary coil of device is connected with the anode of described 4th diode, and the negative electrode of described 4th diode leads to successively
Cross the 6th resistance and the 5th resistance eutral grounding, the input by described 8th resistance Yu optocoupler of the negative electrode of described 4th diode
The anode of end connects, the negative electrode of described controllable accurate source of stable pressure and anode respectively with the negative electrode of the input of described optocoupler and
Ground connects, and the reference pole of described controllable accurate source of stable pressure is connected with the common port of described 5th resistance and the 6th resistance, institute
The negative electrode stating controllable accurate source of stable pressure is connected with the anode of described optocoupler input by described 7th resistance, described controlled
The negative electrode of precision voltage regulator passes sequentially through the 6th electric capacity and the 9th resistance and described 5th resistance and the common port of the 6th resistance
Connecting, the colelctor electrode of the outfan of described optocoupler and emitter-base bandgap grading are connected with feedback end and the ground of described power drives chip respectively,
When the feedback end of described power drives chip is described second MOS switch pipe cut-off under low level state, when described electricity
Under the state that the feedback end of source drive chip is high level, the open the light base stage of pipe of described 2nd MOS is connected with pwm signal.
2. switching power circuit as claimed in claim 1, is characterized in that: also include the 3rd resistance, the 4th resistance,
First electric capacity and the 3rd diode, the first end of the primary coil of described transformator passes sequentially through the first electric capacity, the 4th electricity
Resistance is connected with the negative electrode of the 3rd diode, the anode of described 3rd diode and the second of the primary coil of described transformator
End connects, and two ends with described first electric capacity respectively, the two ends of described 3rd resistance are connected.
3. switching power circuit as claimed in claim 1, is characterized in that: also include the 3rd electric capacity, described 3rd electricity
The two ends held are connected with the negative electrode of the 4th diode and the second end of transformer secondary coil respectively.
4. switching power circuit as claimed in claim 1, is characterized in that: described pwm control circuit also includes the 7th
Electric capacity, the negative electrode of described optocoupler input is connected to ground by described 7th electric capacity.
5. switching power circuit as claimed in claim 1, is characterized in that: also include the second electric capacity, described transformator
The first end of primary coil be connected to ground by described second electric capacity.
6. switching power circuit as claimed in claim 1, is characterized in that: described controllable accurate source of stable pressure is TL431
Controllable accurate source of stable pressure.
7. switching power circuit as claimed in claim 1, is characterized in that: described power drives chip be comprise described
The NCP1075 power drives chip of the second MOS switch pipe or NCP1072 power drives chip.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410492046.XA CN104253546B (en) | 2014-09-23 | 2014-09-23 | A kind of switching power circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410492046.XA CN104253546B (en) | 2014-09-23 | 2014-09-23 | A kind of switching power circuit |
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| CN104253546A CN104253546A (en) | 2014-12-31 |
| CN104253546B true CN104253546B (en) | 2016-08-10 |
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| CN201410492046.XA Active CN104253546B (en) | 2014-09-23 | 2014-09-23 | A kind of switching power circuit |
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Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106100388B (en) * | 2016-08-19 | 2019-05-03 | 深圳市华星光电技术有限公司 | A kind of power circuit |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5282107A (en) * | 1992-09-01 | 1994-01-25 | Power Integrations, Inc. | Power MOSFET safe operating area current limiting device |
| JP2003274654A (en) * | 2002-03-18 | 2003-09-26 | Nichicon Corp | Switching power source |
| CN201440643U (en) * | 2009-05-12 | 2010-04-21 | 深圳长城开发科技股份有限公司 | Electronic kilowatt-hour meter and serial switch power supply thereof |
| CN103683204A (en) * | 2012-09-26 | 2014-03-26 | 深圳市海洋王照明工程有限公司 | Switching power supply over-current protection circuit |
| CN203057005U (en) * | 2012-11-13 | 2013-07-10 | 范青青 | Switching power supply device of air purifier |
| CN203027129U (en) * | 2012-11-26 | 2013-06-26 | 西安威正电子科技有限公司 | RCD (Residual Current Device) circuit for reducing voltage stress of switching power supply MOS (Metal Oxide Semiconductor) tube |
| CN204119070U (en) * | 2014-09-23 | 2015-01-21 | 惠州市可立克科技有限公司 | A kind of switching power circuit |
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Effective date of registration: 20190424 Address after: 342100 Jiulong District, Anyuan County Industrial Park, Ganzhou City, Jiangxi Province Patentee after: Anyuan Meijing Electronics Co., Ltd. Address before: 516006 Dongjiang Hi-tech Industrial Park, Zhongkai Hi-tech Zone, Huizhou City, Guangdong Province (No. 2, Xingde West Road, Dongjiang Hi-tech Industrial Park, Dongxing District) Patentee before: Huizhou Click Technology Co., Ltd. |
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