CN104682685A - Power supply under-voltage protection circuit of isolating switch - Google Patents
Power supply under-voltage protection circuit of isolating switch Download PDFInfo
- Publication number
- CN104682685A CN104682685A CN201310632314.9A CN201310632314A CN104682685A CN 104682685 A CN104682685 A CN 104682685A CN 201310632314 A CN201310632314 A CN 201310632314A CN 104682685 A CN104682685 A CN 104682685A
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- CN
- China
- Prior art keywords
- power supply
- voltage
- transformer
- isolating switch
- operational amplifier
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/36—Means for starting or stopping converters
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Amplifiers (AREA)
Abstract
The invention relates to a power supply under-voltage protection circuit of an isolating switch. The power supply under-voltage protection circuit of the isolating switch comprises an operational amplifier U1 and a transformer T1, wherein the normal-phase end of the operational amplifier U1 is connected with one end of a second resistor R2 and one end of a first resistor R1, the other end of the second resistor R2 is grounded, the other end of the first resistor R1 is connected with VCC, the reverse-phase end of the operational amplifier U1 is connected with comparison voltage Verf, the output end of the operational amplifier U1 is connected with the input end of a PWM (Pulse Width Modulation) control circuit, the output end of the PWM control circuit is connected with the grid of an N-channel MOS (Metal Oxide Semiconductor) transistor Q1, the source of the N-channel MOS transistor Q1 is grounded, the drain is connected with one end of the primary coil of the transformer T1, and the other end of the primary coil of the transformer T1 is connected with the VCC. By adopting a divider resistance manner and an operational amplifier circuit, the isolating switch can work only when the input voltage is higher than certain Vref and the risk of low voltage and large current is avoided. The switch power supply starts to work only after the input voltage reaches a certain extent and the input voltage has already been higher when the power supply works.
Description
Technical field
The invention belongs to power technique fields, particularly a kind of isolating switch power under-voltage protecting circuit.
Background technology
Switching Power Supply utilizes modern power electronics technology, the time ratio that control switch pipe turns on and off, and maintain a kind of power supply of regulated output voltage, Switching Power Supply is generally made up of pulse width modulation (PWM) control IC and MOSFET.In current isolating switch power, do not have input undervoltage circuit, cause when inputting power-off or low-voltage, switching voltage is just started working, and there is the risk of low-voltage, high-current.
Summary of the invention
In order to overcome the shortcoming of above-mentioned prior art, the object of the present invention is to provide a kind of isolating switch power under-voltage protecting circuit, the signal amplification characteristic, the driving force amplification characteristic that make use of electric resistance partial pressure characteristic and amplifier are protected.
To achieve these goals, the technical solution used in the present invention is:
A kind of isolating switch power under-voltage protecting circuit; comprise amplifier U1 and transformer T1; one end of positive termination second resistance R2 of amplifier U1 and one end of the first resistance R1; the another end ground connection of the second resistance R2; another termination VCC of first resistance R1; the anti-phase termination comparative voltage Verf of amplifier U1; the input of the output termination pwm control circuit of amplifier U1; the grid of the output termination N-channel MOS pipe Q1 of pwm control circuit; the source ground of N-channel MOS pipe Q1; drain electrode connects primary coil one end of transformer T1, another termination VCC of primary coil of transformer T1.
Compared with prior art, the present invention adopts mode and the amplifier amplifying circuit of divider resistance, input voltage must could be worked higher than certain Vref, avoid the risk of low-voltage, high-current.After input voltage acquires a certain degree, Switching Power Supply is just started working, and during arrival power work, input voltage is higher.
Accompanying drawing explanation
Fig. 1 is structural representation of the present invention.
Embodiment
Embodiments of the present invention are described in detail below in conjunction with drawings and Examples.
As shown in Figure 1, a kind of isolating switch power under-voltage protecting circuit, comprise amplifier U1 and transformer T1, one end of positive termination second resistance R2 of amplifier U1 and one end of the first resistance R1, the another end ground connection of the second resistance R2, another termination VCC of first resistance R1, the anti-phase termination comparative voltage Verf of amplifier U1, the input of the output termination pwm control circuit of amplifier U1, the grid of the output termination N-channel MOS pipe Q1 of pwm control circuit, the source ground of N-channel MOS pipe Q1, drain electrode connects primary coil one end of transformer T1, another termination VCC of primary coil of transformer T1.
In the present invention, when input Vin starts to rise, before not reaching setting voltage, amplifier U1 exports as low level, and pwm control circuit does not export PWM drive singal after judging, T1 does not work, and causes module no-output.
After Vin rises to set point, U1 output voltage high level, export PWM drive singal after pwm control circuit judges, T1 works, circuit output voltage Vout.
The effect of R1 and R2 is to Vin dividing potential drop, and reduce the controlling value of input voltage, under-voltage threshold is Vref*(R1+R2)/R2.
Claims (1)
1. an isolating switch power under-voltage protecting circuit, it is characterized in that, comprise amplifier U1 and transformer T1, one end of positive termination second resistance R2 of amplifier U1 and one end of the first resistance R1, the another end ground connection of the second resistance R2, another termination VCC of first resistance R1, the anti-phase termination comparative voltage Verf of amplifier U1, the input of the output termination pwm control circuit of amplifier U1, the grid of the output termination N-channel MOS pipe Q1 of pwm control circuit, the source ground of N-channel MOS pipe Q1, drain electrode connects primary coil one end of transformer T1, another termination VCC of primary coil of transformer T1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310632314.9A CN104682685A (en) | 2013-11-28 | 2013-11-28 | Power supply under-voltage protection circuit of isolating switch |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310632314.9A CN104682685A (en) | 2013-11-28 | 2013-11-28 | Power supply under-voltage protection circuit of isolating switch |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN104682685A true CN104682685A (en) | 2015-06-03 |
Family
ID=53317386
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310632314.9A Pending CN104682685A (en) | 2013-11-28 | 2013-11-28 | Power supply under-voltage protection circuit of isolating switch |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104682685A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106100312A (en) * | 2016-08-25 | 2016-11-09 | 贵州航天凯山石油仪器有限公司 | A kind of DC source start-up circuit being applicable to high input impedance |
| CN106841761A (en) * | 2017-04-05 | 2017-06-13 | 王金锁 | A kind of input undervoltage alarm detection circuit arrangement based on divider resistance |
| CN111555602A (en) * | 2020-05-27 | 2020-08-18 | 深圳市元征科技股份有限公司 | Power supply control circuit and power supply device of DC-DC chip |
-
2013
- 2013-11-28 CN CN201310632314.9A patent/CN104682685A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106100312A (en) * | 2016-08-25 | 2016-11-09 | 贵州航天凯山石油仪器有限公司 | A kind of DC source start-up circuit being applicable to high input impedance |
| CN106100312B (en) * | 2016-08-25 | 2018-08-28 | 贵州航天凯山石油仪器有限公司 | A kind of DC power supply start-up circuit suitable for high input impedance |
| CN106841761A (en) * | 2017-04-05 | 2017-06-13 | 王金锁 | A kind of input undervoltage alarm detection circuit arrangement based on divider resistance |
| CN111555602A (en) * | 2020-05-27 | 2020-08-18 | 深圳市元征科技股份有限公司 | Power supply control circuit and power supply device of DC-DC chip |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20150603 |