CN204651917U - Data-interface protective circuit - Google Patents
Data-interface protective circuit Download PDFInfo
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- CN204651917U CN204651917U CN201520400461.8U CN201520400461U CN204651917U CN 204651917 U CN204651917 U CN 204651917U CN 201520400461 U CN201520400461 U CN 201520400461U CN 204651917 U CN204651917 U CN 204651917U
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- power supply
- nmos tube
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- comparator
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- 230000001681 protective effect Effects 0.000 title claims abstract description 12
- 239000000758 substrate Substances 0.000 claims abstract description 7
- 239000004065 semiconductor Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000013480 data collection Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
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Abstract
Data-interface protective circuit, between the feeder ear being connected to mobile device data interface and bus end, be made up of comparator, the first NMOS tube, the second NMOS tube, the first diode, the second diode, the first DC power supply, the second DC power supply, current-limiting resistance, the first pull-up resistor and the second pull-up resistor; The output of described comparator connects the grid of two NMOS tube, and the substrate of two NMOS tube connects feeder ear and bus end respectively, and is connected with respective drain electrode; The magnitude of voltage of described second DC power supply is greater than the first DC power supply.The utility model can realize the available protecting to mobile device USB power source output line, and no matter USB power source output line VBUS occurs power supply or shorted to earth, does not all affect the normal work of mobile device internal circuit, achieves reliable short-circuit protection.
Description
Technical field
The utility model relates to electronic circuit field, particularly, relates to a kind of data-interface protective circuit.
Background technology
In order to ensure use safety, mobile device, the security performance of the mobile unit such as used during field data collection requires very high, just will ensure that rate of breakdown is as far as possible low when designing.As communication interface between the mobile peripheral hardware be most widely used at present and main frame, USB(Universal Serial Bus) have cost low, use simple, support plug and play, be easy to the features such as expansion, car entertainment and memory device obtain a wide range of applications.Because USB interface provides built-in power, can provide the electric current of more than 500mA, for the equipment that some power are larger, as portable hard drive etc., its instant drive current then can reach more than 1A.For usb bus is this can the interface of direct out-put supply, the situation of interface circuit to power supply or shorted to earth may be there is, now will damage body.
Utility model content
The mobile device interface of supplying power for outside charging can there is to damage big current when power supply or ground short circuit the technological deficiency of internal components and equipment for overcoming, the utility model discloses a kind of data-interface protective circuit.
Data-interface protective circuit, between the feeder ear being connected to mobile device data interface and bus end, it is characterized in that, be made up of comparator, the first NMOS tube, the second NMOS tube, the first diode, the second diode, the first DC power supply, the second DC power supply, current-limiting resistance, the first pull-up resistor and the second pull-up resistor;
The output of described comparator connects the grid of two NMOS tube, the substrate of two NMOS tube connects feeder ear and bus end respectively, and be connected with respective drain electrode, the source electrode of two NMOS tube is interconnected, and connect the positive pole of the first diode, current-limiting resistance is connected between the negative pole comparator inverting input of the first diode, comparator normal phase input end connects the first DC power supply by the second pull-up resistor, and connect the second diode cathode, second diode cathode connects bus end, compares output and connects the second DC power supply by the first pull-up resistor;
The magnitude of voltage of described second DC power supply is greater than the first DC power supply.
Preferably, light-emitting diode is connected with between described comparator output terminal to ground.
Preferably, the first electric capacity and limit resistance is connected between described current-limiting resistance two ends and ground.
Preferably, the second electric capacity is connected with between described comparator normal phase input end and ground.
Data-interface protective circuit described in the utility model; the available protecting to mobile device USB power source output line can be realized; no matter USB power source output line VBUS occurs power supply or shorted to earth, does not all affect the normal work of mobile device internal circuit, achieves reliable short-circuit protection.By the common separation device that use cost is extremely low, significantly reduce manufacturing cost.
Accompanying drawing explanation
Fig. 1 is a kind of embodiment schematic diagram of the utility model;
Mark and corresponding parts title in accompanying drawing: VIN-feeder ear, VBUS-first divider resistance, VCC1-first DC power supply, VCC2-second DC power supply, COMP-comparator, R1 – current-limiting resistance, R2-limit resistance, R3-first pull-up resistor, R4-second pull-up resistor, D1-first diode, D2-second diode, D3-light-emitting diode, C1 – first electric capacity, C2-second electric capacity, M1-first NMOS tube, M2-second NMOS tube.
Embodiment
Below in conjunction with embodiment and accompanying drawing, to the detailed description further of the utility model do, but execution mode of the present utility model is not limited thereto.
Data-interface protective circuit described in the utility model, between the feeder ear being connected to mobile device data interface and bus end, it is characterized in that, be made up of comparator, the first NMOS tube, the second NMOS tube, the first diode, the second diode, the first DC power supply, the second DC power supply, the first divider resistance, the second divider resistance, the first pull-up resistor and the second pull-up resistor;
The output of described comparator connects the grid of two NMOS tube, the substrate of two NMOS tube connects feeder ear and bus end respectively, and be connected with respective drain electrode, the source electrode of two NMOS tube is interconnected, and connect the positive pole of the first diode, current-limiting resistance is connected between the negative pole comparator inverting input of the first diode, comparator normal phase input end connects the first DC power supply by the second pull-up resistor, and connect the second diode cathode, second diode cathode connects bus end, compares output and connects the second DC power supply by the first pull-up resistor;
The magnitude of voltage of described second DC power supply is greater than the first DC power supply.
Such as the first DC power supply gets 3.3V, and the second DC power supply gets 12V, and now for feeder ear, input voltage should between 3.3 to 12V, such as, be 5V.
For two NMOS tube, drain electrode is P district, substrate is N district, substrate is connected with drain electrode, form the diode pointing to substrate from drain electrode, for the source electrode A point that two NMOS tube link together, when entering external device in VBUS termination, no matter VBUS terminal voltage is higher or lower than 5V, is all the higher person between VBUS end and VIN end at A point voltage.
When VBUS terminal voltage is outside the first DC power supply and the second direct current power source voltage interval value, when being namely greater than 12V or being less than 3.3V, such as when being less than 3.3V, A point voltage is 5V, inputted in comparator anti-phase input terminal voltage by the first diode D1 and current-limiting resistance, and because VBUS voltage is lower than 3.3V, make the second diode current flow, at comparator normal phase input end, voltage is the value lower than 3.3V, comparator output low level, close two metal-oxide-semiconductors, avoid VBUS terminal voltage too low, namely during common short circuit grounding, cause short circuit between VIN and ground.And when VBUS voltage is higher than 5V, A point voltage is VBUS voltage, but the second diode not conducting, make comparator normal phase input end voltage still be the 3.3V of the first DC power supply, comparator normal phase input end input voltage is higher than 5V, and output voltage is still negative value, two metal-oxide-semiconductors keep closing, now do not charge, avoid electric current to pour in down a chimney 5V voltage, infringement battery.
And when VBUS voltage is higher than the second DC power supply 12V, due to now for the second NMOS tube, grid voltage is limited in 12V by VCC2, and VGS has become negative value, M2 can not conducting, avoids high pressure to damage internal components.
A light-emitting diode D3 can be set at comparator output terminal, both positive and negative polarity connects comparator output terminal and ground respectively, positive voltage is exported at comparator, when two NMOS tube are opened, D3 is luminous, points out now data-interface normal, as D3 does not work, then comparator output low level, represents access power supply amplitude over range.
The utility model A point feeds back to comparator inverting input, an actual formation feedback control loop, for improving loop stability, the measure in input termination capacitor can be taked, such as between described current-limiting resistance two ends and ground, be connected to the first electric capacity and limit resistance, or the second electric capacity is connected with between described comparator normal phase input end and ground, a dominant pole can be provided, wherein first kind of way is more complicated, usual limit resistance R2 resistance is much larger than R1, weaken R1 as far as possible, the voltage variations affect brought at comparator input terminal that R2 dividing potential drop is brought, R2 and C1 provides a dominant pole jointly, by the adjustment to R2, better can regulate the position of dominant pole, this and the second way are only connected C2 electric capacity at input, the input impedance Fuzzy Processing of comparator is compared, more accurate.
As mentioned above, the utility model can be realized preferably.
Claims (4)
1. data-interface protective circuit, between the feeder ear being connected to mobile device data interface and bus end, it is characterized in that, be made up of comparator, the first NMOS tube, the second NMOS tube, the first diode, the second diode, the first DC power supply, the second DC power supply, current-limiting resistance, the first pull-up resistor and the second pull-up resistor;
The output of described comparator connects the grid of two NMOS tube, the substrate of two NMOS tube connects feeder ear and bus end respectively, and be connected with respective drain electrode, the source electrode of two NMOS tube is interconnected, and connect the positive pole of the first diode, current-limiting resistance is connected between the negative pole comparator inverting input of the first diode, comparator normal phase input end connects the first DC power supply by the second pull-up resistor, and connect the second diode cathode, second diode cathode connects bus end, compares output and connects the second DC power supply by the first pull-up resistor;
The magnitude of voltage of described second DC power supply is greater than the first DC power supply.
2. data-interface protective circuit according to claim 1, is characterized in that, is connected with light-emitting diode between described comparator output terminal to ground.
3. data-interface protective circuit according to claim 1, is characterized in that, is connected to the first electric capacity and limit resistance between described current-limiting resistance two ends and ground.
4. data-interface protective circuit according to claim 1, is characterized in that, is connected with the second electric capacity between described comparator normal phase input end and ground.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520400461.8U CN204651917U (en) | 2015-06-11 | 2015-06-11 | Data-interface protective circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520400461.8U CN204651917U (en) | 2015-06-11 | 2015-06-11 | Data-interface protective circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN204651917U true CN204651917U (en) | 2015-09-16 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201520400461.8U Active CN204651917U (en) | 2015-06-11 | 2015-06-11 | Data-interface protective circuit |
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| Country | Link |
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| CN (1) | CN204651917U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104882869A (en) * | 2015-06-11 | 2015-09-02 | 国网四川省电力公司南充供电公司 | Mobile device data interface protective circuit |
-
2015
- 2015-06-11 CN CN201520400461.8U patent/CN204651917U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104882869A (en) * | 2015-06-11 | 2015-09-02 | 国网四川省电力公司南充供电公司 | Mobile device data interface protective circuit |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |