CN201877799U - Universal serial bus (USB) protection circuit - Google Patents
Universal serial bus (USB) protection circuit Download PDFInfo
- Publication number
- CN201877799U CN201877799U CN2010206372927U CN201020637292U CN201877799U CN 201877799 U CN201877799 U CN 201877799U CN 2010206372927 U CN2010206372927 U CN 2010206372927U CN 201020637292 U CN201020637292 U CN 201020637292U CN 201877799 U CN201877799 U CN 201877799U
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- usb
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- voltage comparator
- circuit
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Abstract
The utility model discloses a universal serial bus (USB) protection circuit, which is formed by interconnecting a power switch circuit, an overcurrent test circuit and an overcurrent alarm circuit. The USB protection circuit can be used in a device which communicates or takes power supply through a USB interface and can effectively protect the USB interface of an electronic product and the USB device. When the inner circuit of the device that uses the USB interface protection circuit is short-circuited, the power supply of the USB interface is cut of by the USB interface protection circuit in an instant so as to effectively protect the USB interface of the electronic product; and at the same time, a buzzer sounds, so that repairing personnel can deal in time.
Description
Technical field
The utility model relates to a kind of protective circuit, specifically, relates to a kind of a kind of USB protective circuit that is applicable to consumption electronic product or flash memory device.
Background technology
At present, USB interface has become the mouth common interfaces of consumption electronic product digital camera, MP3, mobile phone or flash memory device portable hard drive, carry out exchanges data by USB interface, because the current capacity of general USB interface is all very little, so if designed USB device is owing to reasons such as internal short-circuits, cause the USB interface overcurrent, will cause the damage of electronic product, cause unnecessary economic loss.
Summary of the invention
Technical assignment of the present utility model is to provide a kind of USB protective circuit at above the deficiencies in the prior art.
The technical scheme that its technical problem that solves the utility model adopts is: a kind of USB protective circuit, comprise power switch circuit, the overcurrent test circuit, the overcurrent warning circuit, wherein, power switch circuit is by resistance R 4, PNP triode Q2 forms, the end of R4 links to each other with the base stage of triode Q2, the other end of R4 links to each other with the output of voltage comparator U2A, the emitter of triode Q2 meets USB power supply output cathode VCCO, the collector electrode of triode Q2 meets the VCC of USB device, the overcurrent test circuit is by resistance R 1, R2, R3, diode D1, voltage comparator U2A forms, the ground GND of one termination USB device of resistance R 1, another termination USB power supply output negative pole GNDO of resistance R 1, the anode of diode D1 connects the inverting input of voltage comparator U2A, the negative electrode of diode D1 meets USB power supply output negative pole GNDO, the anode of resistance R 2 one terminating diode D1, resistance R 2 another termination USB power supply output cathode VCCO, the negative supply of voltage comparator U2A meets GNDO, and the positive supply of voltage comparator U2A meets VCCO; The in-phase input end of voltage comparator U2A meets the ground GND of USB device, and the output of voltage comparator U2A connects the base stage of Q2 by resistance R 4, and the output of voltage comparator U2A meets VCCO by resistance R 3 simultaneously; The overcurrent warning circuit is by resistance R 5, R6, and PNP triode Q1 and buzzer U3 form, a termination VCC of resistance R 5, another termination GDNO, resistance R 6 one termination VCC, the base stage of another termination PNP triode Q1, the emitter of Q1 meets VCCO, and collector electrode meets GNDO by buzzer U3.
The beneficial effects of the utility model are when the USB device internal short-circuit causes overcurrent, can effectively protect the USB interface and the USB device of electronic product mainboard, and convenient and practical, cost is low.
Description of drawings
Fig. 1 is an electrical block diagram of the present utility model.
Embodiment
Below in conjunction with Figure of description the utility model is done following detailed explanation.
As shown in the figure, a kind of USB protective circuit, be formed by connecting by power switch circuit, overcurrent test circuit, overcurrent warning circuit, power switch circuit is by resistance R 4, PNP triode Q2 forms, and the end of R4 links to each other with the base stage of triode Q2, and the other end of R4 links to each other with the output of voltage comparator U2A, the emitter of triode Q2 meets USB power supply output cathode VCCO, and the collector electrode of triode Q2 meets the VCC of USB device; The overcurrent test circuit is by resistance R 1, R2, R3, diode D1, voltage comparator U2A forms, the ground GND of one termination USB device of resistance R 1, another termination USB power supply output negative pole GNDO of resistance R 1, the anode of diode D1 connects the inverting input of voltage comparator U2A, the negative electrode of diode D1 meets USB power supply output negative pole GNDO, the anode of resistance R 2 one terminating diode D1, resistance R 2 another termination USB power supply output cathode VCCO, the negative supply of voltage comparator U2A meets GNDO, and the positive supply of voltage comparator U2A meets VCCO; The in-phase input end of voltage comparator U2A meets the ground GND of USB device, and the output of voltage comparator U2A connects the base stage of Q2 by resistance R 4, presses the output of comparator UZA to meet VCCO by resistance R 3 simultaneously; The overcurrent warning circuit is by resistance R 5, R6, and PNP triode Q1 and buzzer U3 form, a termination VCC of resistance R 5, another termination GDNO, resistance R 6 one termination VCC, the base stage of another termination PNP triode Q1, the emitter of Q1 meets VCCO, and collector electrode meets GNDO by buzzer U3; When the USB device internal short-circuit, the electric current that flows through resistance R 1 becomes big suddenly, voltage between GND and the GNDO raises, when the electric current that flows through resistance R 1 during greater than the electric current set, the voltage of the in-phase input end of voltage comparator U2A will be greater than inverting input voltage, the output of voltage comparator U2A will become high level, and PNP triode Q2 turn-offs, and has cut off the USB interface power supply; PNP triode Q1 road is logical simultaneously, and buzzer U3 is with sounding.
Claims (1)
1. USB protective circuit, comprise power switch circuit, the overcurrent test circuit, the overcurrent warning circuit, it is characterized in that: power switch circuit is by resistance R 4, PNP triode Q2 forms, the end of R4 links to each other with the base stage of triode Q2, the other end of R4 links to each other with the output of voltage comparator U2A, the emitter of triode Q2 meets USB power supply output cathode VCCO, the collector electrode of triode Q2 meets the VCC of USB device, the overcurrent test circuit is by resistance R 1, R2, R3, diode D1, voltage comparator U2A forms, the ground GND of one termination USB device of resistance R 1, another termination USB power supply output negative pole GNDO of resistance R 1, the anode of diode D1 connects the inverting input of voltage comparator U2A, and the negative electrode of diode D1 meets USB power supply output negative pole GNDO, the anode of resistance R 2 one terminating diode D1, resistance R 2 another termination USB power supply output cathode VCCO, the negative supply of voltage comparator U2A meets GNDO, and the positive supply of voltage comparator U2A meets VCCO; The in-phase input end of voltage comparator U2A meets the ground GND of USB device, and the output of voltage comparator U2A connects the base stage of Q2 by resistance R 4, and the output of voltage comparator U2A meets VCCO by resistance R 3 simultaneously; The overcurrent warning circuit is by resistance R 5, R6, and PNP triode Q1 and buzzer U3 form, a termination VCC of resistance R 5, another termination GDNO, resistance R 6 one termination VCC, the base stage of another termination PNP triode Q1, the emitter of Q1 meets VCCO, and collector electrode meets GNDO by buzzer U3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010206372927U CN201877799U (en) | 2010-11-19 | 2010-11-19 | Universal serial bus (USB) protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010206372927U CN201877799U (en) | 2010-11-19 | 2010-11-19 | Universal serial bus (USB) protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201877799U true CN201877799U (en) | 2011-06-22 |
Family
ID=44165708
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010206372927U Expired - Fee Related CN201877799U (en) | 2010-11-19 | 2010-11-19 | Universal serial bus (USB) protection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201877799U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103747406A (en) * | 2013-12-21 | 2014-04-23 | 柳州航盛科技有限公司 | Safe-type detection tool used for vehicle-mounted sound device |
| CN103853685A (en) * | 2012-11-30 | 2014-06-11 | 英业达科技有限公司 | Universal serial bus circuit and operation method thereof |
-
2010
- 2010-11-19 CN CN2010206372927U patent/CN201877799U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103853685A (en) * | 2012-11-30 | 2014-06-11 | 英业达科技有限公司 | Universal serial bus circuit and operation method thereof |
| CN103747406A (en) * | 2013-12-21 | 2014-04-23 | 柳州航盛科技有限公司 | Safe-type detection tool used for vehicle-mounted sound device |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20110622 Termination date: 20111119 |