CN212811285U - Overcurrent protection circuit and electronic device detection equipment - Google Patents
Overcurrent protection circuit and electronic device detection equipment Download PDFInfo
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- CN212811285U CN212811285U CN202022110292.8U CN202022110292U CN212811285U CN 212811285 U CN212811285 U CN 212811285U CN 202022110292 U CN202022110292 U CN 202022110292U CN 212811285 U CN212811285 U CN 212811285U
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Abstract
The utility model relates to an overcurrent protection circuit technical field especially relates to an overcurrent protection circuit and electron device check out test set, overcurrent protection circuit includes MOS pipe Q1, instrumentation amplifier U1, switch circuit B2, MOS pipe Q1's source electrode is connected with instrumentation amplifier U1's positive input end, the first power end V1 electricity of power, MOS pipe Q1's drain electrode is connected with instrumentation amplifier U1's negative input end, current output end VOUT electricity, switch circuit B2 includes first switch input end B21, second switch input end B22, switch output end B23, first switch input end B21 is connected with the second power end V2 electricity of power, second switch input end B22 is connected with instrumentation amplifier U1's output electricity, switch output end B23 is connected with MOS pipe Q1's grid electricity; the utility model discloses an overcurrent protection circuit consumption is extremely low, can not produce a large amount of heats, and overall circuit structure is simple, wholly use the device less, whole volume is less, and the practicality is stronger.
Description
The technical field is as follows:
the utility model relates to an overcurrent protection circuit technical field especially relates to an overcurrent protection circuit and electron device check out test set.
Background art:
circuit modules of electronic products each include a circuit board and a large number of electronic devices plugged onto the circuit board, and if a bad electronic device is plugged onto the circuit board during the production process, problems may occur in the function or performance of the entire circuit board. At this time, a great deal of time is needed for repairing, and the repairing is more difficult, so that the repairing cost is higher. Therefore, it is necessary to detect each electronic device before the electronic device is used, and detect out the bad electronic device, so as to reduce the problem that the bad electronic device is repaired after being plugged into the circuit board. With the development of automation technology, most of the existing electronic devices are automatically detected by electronic device detection equipment.
In order to prevent the electronic device detection equipment from supplying excessive current, the electronic device detection equipment is provided with an overcurrent protection circuit, however, the overcurrent protection circuit of the existing electronic device detection equipment mostly performs current sampling by a method of connecting sampling resistors in series, so that not only are a plurality of devices used and the whole volume is large, but also a large amount of power is often required to be consumed in order to obtain a large enough sampling signal, the power consumption is increased, and the problem of heat generation is caused.
The utility model has the following contents:
the utility model aims to provide an overcurrent protection circuit aiming at the defects of the prior art, the overcurrent protection function can be realized without sampling resistance to sample current, the power consumption is extremely low, a large amount of heat can not be generated, the whole circuit structure is simple, the whole used devices are fewer, and the whole volume is smaller; the utility model also provides an electron device check out test set has the overcurrent protection function, and the practicality is stronger.
In order to realize the purpose, the utility model discloses a technical scheme is: an overcurrent protection circuit comprises a MOS tube Q1, an instrumentation amplifier U1 and a switch circuit B2, wherein a source electrode of the MOS tube Q1 is electrically connected with a positive input end of the instrumentation amplifier U1 and a first power supply end V1 of a power supply, a drain electrode of the MOS tube Q1 is electrically connected with a negative input end of the instrumentation amplifier U1 and a current output end VOUT, the switch circuit B2 comprises a first switch input end B21, a second switch input end B22 and a switch output end B23, the first switch input end B21 is electrically connected with a second power supply end V2 of the power supply, the second switch input end B22 is electrically connected with an output end of the instrumentation amplifier U1, and the switch output end B23 is electrically connected with a grid electrode of the MOS tube Q1.
In a further improvement of the above scheme, the switch circuit B2 includes a comparator U2, a resistor R1, and a resistor R2, one end of the resistor R1 is used as a first switch input B21 of the switch circuit B2, the other end of the resistor R1 is electrically connected to the negative input terminal of the comparator U2 and ground, a resistor R2 is connected in series between the resistor R1 and ground, the positive input terminal of the comparator U2 is used as a second switch input B22 of the switch circuit B2, and the output terminal of the comparator U2 is used as a switch output B23 of the switch circuit B2.
In a further improvement of the above scheme, the comparator U2 is of the type LM 311.
In a further improvement of the above scheme, the MOS transistor Q1 is a P-type MOS transistor.
The further improvement of the scheme is that the model of the MOS transistor Q1 is A03401A.
In a further improvement of the above solution, the instrumentation amplifier U1 is of type INA 828.
An electronic device detection device comprises a power supply, a load circuit B3 and an overcurrent protection circuit according to any one of the above schemes, wherein a current output end VOUT of the overcurrent protection circuit is electrically connected with an input end of a load circuit B3.
The utility model has the advantages that: the utility model provides a pair of overcurrent protection circuit, including MOS pipe Q1, instrument amplifier U1, switch circuit B2, MOS pipe Q1's source and instrument amplifier U1's positive input, the first power end V1 electricity of power is connected, MOS pipe Q1's drain electrode is connected with instrument amplifier U1's negative direction input, current output end VOUT electricity, switch circuit B2 includes first switch input B21, second switch input B22, switch output B23, first switch input B21 is connected with the second power end V2 electricity of power, second switch input B22 is connected with instrument amplifier U1's output electricity, switch output B23 is connected with MOS pipe Q1's grid electricity; the over-current protection circuit of the utility model generates voltage difference through the internal resistance RDS between the source electrode and the drain electrode of the MOS tube Q1, the voltage difference generated by the internal resistance RDS between the source electrode and the drain electrode of the MOS tube Q1 is increased along with the increase of output current, the generated voltage difference is amplified by the instrumentation amplifier U1 and then is sent to the second switch input end B22 of the switch circuit B2, when the amplified voltage difference is more than or equal to the preset voltage threshold value, the switch circuit B2 outputs high level and pulls up the grid voltage of the MOS tube Q1, the switch circuit B2 turns off the MOS tube Q1, the current output end VOUT is limited, the over-current protection circuit of the utility model can play the over-current protection role without sampling resistance to sample current, not only has extremely low power consumption and can not generate a large amount of heat, but also has simple structure, less devices are used integrally, smaller overall volume and stronger practicability, can be suitable for various use occasions.
Description of the drawings:
fig. 1 is a circuit schematic diagram of the overcurrent protection circuit of the present invention.
Fig. 2 is a circuit schematic diagram of the overcurrent protection circuit of the present invention.
Fig. 3 is a schematic circuit diagram of the electronic device detecting apparatus of the present invention.
The specific implementation mode is as follows:
embodiment 1, as shown in fig. 1-2, an overcurrent protection circuit B1 includes a MOS transistor Q1, an instrumentation amplifier U1, and a switch circuit B2, where a source of the MOS transistor Q1 is electrically connected to a positive input terminal of the instrumentation amplifier U1 and a first power supply terminal V1 of a power supply, a drain of the MOS transistor Q1 is electrically connected to a negative input terminal of the instrumentation amplifier U1 and a current output terminal VOUT, a switch circuit B2 includes a first switch input terminal B21, a second switch input terminal B22 and a switch output terminal B23, the first switch input terminal B21 is electrically connected to the second power supply terminal V2 of the power supply, the second switch input terminal B22 is electrically connected to an output terminal of the instrumentation amplifier U1, and the switch output terminal B23 is electrically connected to a gate of the MOS transistor Q1; the overcurrent protection circuit B1 generates a voltage difference through the internal resistance RDS between the source electrode and the drain electrode of the MOS tube Q1, the voltage difference generated by the internal resistance RDS between the source electrode and the drain electrode of the MOS tube Q1 is increased along with the increase of the output current, the generated voltage difference is amplified by the instrumentation amplifier U1 and then is sent to the second switch input end B22 of the switch circuit B2, when the amplified voltage difference is greater than or equal to the preset voltage threshold, the switch circuit B2 outputs high level and pulls up the grid voltage of the MOS tube Q1, the switch circuit B2 turns off the MOS tube Q1, the current output end VOUT is limited, the over-current protection circuit B1 of the utility model can play the role of over-current protection without sampling resistance to sample current, not only has extremely low power consumption and can not generate a large amount of heat, and the whole circuit structure is simple, the whole used devices are fewer, the whole volume is smaller, the practicability is stronger, and the circuit can be suitable for various use occasions.
The switch circuit B2 includes a comparator U2, a resistor R1, and a resistor R2, wherein one end of the resistor R1 is used as a first switch input B21 of the switch circuit B2, the other end of the resistor R1 is electrically connected to the negative input terminal of the comparator U2 and ground, the resistor R2 is connected in series between the resistor R1 and ground, the positive input terminal of the comparator U2 is used as a second switch input B22 of the switch circuit B2, and the output terminal of the comparator U2 is used as a switch output B23 of the switch circuit B2.
The comparator U2 is LM311, not only cheap, but also has high flexibility, can compare, judge output current fast, steadily.
The MOS tube Q1 is a P-type MOS tube, the type of the MOS tube Q1 is A03401A, the characteristics of high blocking voltage and low on-resistance are achieved, and compared with the method of sampling current in series through a sampling resistor, the over-current protection circuit B1 is extremely low in overall power consumption and has good economic benefits.
The type of the instrumentation amplifier U1 is INA828, not only has higher precision, but also has ultra-low power consumption, and is very suitable for an overcurrent protection circuit B1.
Embodiment 2, as shown in fig. 3, an electronic device inspection apparatus includes a power supply, a load circuit B3, and an overcurrent protection circuit B1 in embodiment 1, wherein a current output terminal VOUT of the overcurrent protection circuit B1 is electrically connected to an input terminal of a load circuit B3.
The working principle is as follows:
generating a voltage difference through an internal resistance RDS between a source electrode and a drain electrode of the MOS tube Q1, amplifying the generated voltage difference through an instrumentation amplifier U1, and sending the amplified voltage difference to a second switch input end B22 of a switch circuit B2; the resistor R1 and the resistor R2 divide the power supply voltage, the reference voltage Vref between the resistor R1 and the resistor R2 is used as a comparison value, when the voltage value sent to the second switch input end B22 is higher than or equal to the reference voltage Vref, the switch output end B23 of the comparator U2 outputs high level to the grid electrode of the MOS tube Q1 and pulls up the grid voltage of the MOS tube Q1, the switch circuit B2 turns off the MOS tube Q1, and the current output end VOUT is limited; the utility model discloses an overcurrent protection circuit need not sampling resistor and carries out the current sample and can play the overcurrent protection effect, not only the consumption is extremely low, can not produce a large amount of heats, and overall circuit simple structure, whole use the device less, whole volume is less moreover, and the practicality is stronger, can be applicable to multiple use occasion.
Of course, the above description is only the preferred embodiment of the present invention, so all the equivalent changes or modifications made by the structure, features and principles in accordance with the claims of the present invention are included in the claims of the present invention.
Claims (7)
1. An overcurrent protection circuit, characterized in that: the power supply circuit comprises an MOS tube Q1, an instrumentation amplifier U1 and a switch circuit B2, wherein the source electrode of the MOS tube Q1 is electrically connected with the positive input end of the instrumentation amplifier U1 and a first power supply end V1 of a power supply, the drain electrode of the MOS tube Q1 is electrically connected with the negative input end of the instrumentation amplifier U1 and a current output end VOUT, the switch circuit B2 comprises a first switch input end B21, a second switch input end B22 and a switch output end B23, the first switch input end B21 is electrically connected with a second power supply end V2 of the power supply, the second switch input end B22 is electrically connected with the output end of the instrumentation amplifier U1, and the switch output end B23 is electrically connected with the grid electrode of the MOS tube.
2. An overcurrent protection circuit according to claim 1, wherein: the switch circuit B2 comprises a comparator U2, a resistor R1 and a resistor R2, wherein one end of the resistor R1 is used as a first switch input end B21 of the switch circuit B2, the other end of the resistor R1 is connected with the negative input end of the comparator U2 and the ground, the resistor R2 is connected between the resistor R1 and the ground in series, the positive input end of the comparator U2 is used as a second switch input end B22 of the switch circuit B2, and the output end of the comparator U2 is used as a switch output end B23 of the switch circuit B2.
3. An overcurrent protection circuit according to claim 2, wherein: the model of the comparator U2 is LM 311.
4. An overcurrent protection circuit as claimed in claim 1 or claim 2, wherein: the MOS transistor Q1 is a P-type MOS transistor.
5. An overcurrent protection circuit according to claim 4, wherein: the MOS tube Q1 is A03401A.
6. An overcurrent protection circuit as claimed in claim 1 or claim 2, wherein: the instrumentation amplifier U1 is model INA 828.
7. An electronic device inspection apparatus comprising a power supply, load circuit B3, characterized in that: the overcurrent protection circuit as set forth in any one of claims 1 to 6, further comprising a current output terminal VOUT of the overcurrent protection circuit electrically connected to an input terminal of a load circuit B3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022110292.8U CN212811285U (en) | 2020-09-22 | 2020-09-22 | Overcurrent protection circuit and electronic device detection equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022110292.8U CN212811285U (en) | 2020-09-22 | 2020-09-22 | Overcurrent protection circuit and electronic device detection equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212811285U true CN212811285U (en) | 2021-03-26 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202022110292.8U Active CN212811285U (en) | 2020-09-22 | 2020-09-22 | Overcurrent protection circuit and electronic device detection equipment |
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| Country | Link |
|---|---|
| CN (1) | CN212811285U (en) |
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2020
- 2020-09-22 CN CN202022110292.8U patent/CN212811285U/en active Active
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Address after: 518000 floor 1, No.2, Dongtang Industrial Zone, Chuangxin Road, Shatou community, Shajing street, Bao'an District, Shenzhen City, Guangdong Province Patentee after: Shenzhen Weite Precision Technology Co.,Ltd. Country or region after: China Address before: 518000 1st floor, building 21, Zone C, Liantang Industrial City, Shangcun, Gongming street, Guangming New District, Shenzhen City, Guangdong Province Patentee before: SHENZHEN MICROTEST AUTOMATION Co.,Ltd. Country or region before: China |