CN210838923U - Over-current protection circuit of vehicle-mounted camera - Google Patents
Over-current protection circuit of vehicle-mounted camera Download PDFInfo
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- CN210838923U CN210838923U CN201921747706.9U CN201921747706U CN210838923U CN 210838923 U CN210838923 U CN 210838923U CN 201921747706 U CN201921747706 U CN 201921747706U CN 210838923 U CN210838923 U CN 210838923U
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- 230000005611 electricity Effects 0.000 description 2
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Abstract
The embodiment of the utility model provides an overcurrent protection circuit of vehicle-mounted camera, connect between external power source and vehicle-mounted camera, the circuit includes first triode Q1, second triode Q2, third triode Q3, MOS pipe Q4 and be used for controlling second triode Q2's operating condition's control chip, control chip is including the voltage input pin that is connected to external power source, the level that is connected to the input of third triode Q3 detects the pin and is connected to second triode Q2's control end and the messenger who defaults output high level and stop outputting the high level of high level when the level detects the pin and detects the low level enables the pin, wherein: the input end of the first triode Q1 and the input end of the MOS transistor Q4 are both connected to an external power supply, and the input end and the control end of the first triode Q1 are connected through a first resistor R1; the output end of the MOS tube Q4 is used as the output end of the overcurrent protection circuit and is connected to the vehicle-mounted camera. The circuit element of the embodiment is few, the structure is simple, and the production cost is effectively reduced.
Description
Technical Field
The embodiment of the utility model provides a relate to on-vehicle camera technical field, especially relate to an on-vehicle camera's overcurrent protection circuit.
Background
The existing vehicle-mounted power supply generally needs to carry out overcurrent protection on the camera when supplying power to the vehicle-mounted camera, so that the vehicle-mounted camera is prevented from being burnt out. The existing overcurrent protection circuit is usually realized by adopting a fuse type fuse overcurrent protection, a self-recovery fuse overcurrent or overcurrent protection chip scheme, wherein the overcurrent protection chip scheme is realized by adopting a single chip microcomputer and an overcurrent protection chip to be mutually matched, when the current input by an external power supply or the working current of a vehicle-mounted camera exceeds a preset current value, a corresponding pin of the single chip microcomputer outputs a low level to the overcurrent protection chip, and then the overcurrent protection chip outputs the low level through a control pin to turn off a current output pin of the overcurrent protection chip so as to realize overcurrent protection, but the price of the existing overcurrent protection chip is relatively high, and the production cost is improved.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a technical problem who solves lies in, provides an overcurrent protection circuit of on-vehicle camera, can effective reduction in production cost.
In order to solve the technical problem, an embodiment of the utility model provides a following technical scheme: an overcurrent protection circuit of a vehicle-mounted camera is connected between an external power supply and the vehicle-mounted camera, the circuit comprises a first triode Q1, a second triode Q2, a third triode Q3, a MOS tube Q4 and a control chip for controlling the working state of the second triode Q2, the control chip comprises a voltage input pin connected to the external power supply for obtaining power supply, a level detection pin connected to the input end of the third triode Q3 and an enable pin connected to the control end of the second triode Q2 for outputting a high level by default and stopping outputting the high level when the level detection pin detects a low level, wherein:
the input end of the first triode Q1 and the input end of the MOS transistor Q4 are both connected to the external power supply, the input end and the control end of the first triode Q1 are connected through a first resistor R1, and the output end of the first triode Q1 is connected to the control end of the third triode Q3 and is also grounded through a second resistor R2;
an output end of the second triode Q2 and an output end of the third triode Q3 are both grounded, an input end of the second triode Q2 is connected to a control end of the MOS transistor Q4, and a control end of the second triode Q2 is respectively connected to the enable pin and an input end of the third triode Q3;
the input end and the control end of the MOS tube Q4 are connected through a second resistor R3, and the output end of the MOS tube Q4 is used as the output end of the overcurrent protection circuit and is connected to the vehicle-mounted camera.
Further, the enable pin is switched to output a low level when the level detection pin detects a low level.
Further, the external power supply is also connected to the input end of the MOS transistor Q4 through a fourth resistor R4.
Further, the output terminal of the first transistor Q1 is connected to the control terminal of the third transistor Q3 through a fifth resistor R5.
Furthermore, a sixth resistor R6 and a seventh resistor R7 are connected in series between the control end of the second triode Q2 and the enable pin, and the input end of the third triode Q3 is connected to a line between the sixth resistor R6 and the seventh resistor R7.
Further, the output end of the MOS transistor Q4 is also grounded through a first capacitor C1.
Further, the circuit further comprises a diode D, wherein the anode of the diode D is connected with the output end of the MOS tube Q4, and the cathode of the diode D is connected to the vehicle-mounted camera.
Furthermore, a filter circuit is connected between the negative electrode of the diode D and the vehicle-mounted camera.
Further, the filter circuit includes: a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a first magnetic bead FB1, a second magnetic bead FB2, a first inductor L1, a second inductor L2, an eighth resistor R8, a ninth resistor R9 and an ESD protection diode ESD, wherein the cathode of the diode D is connected to the vehicle-mounted camera through a serial connection body of the first magnetic bead FB1, the eighth resistor R8, the ninth resistor R9 and the second magnetic bead FB2 in sequence, one end of the first magnetic bead FB1, which is connected with the cathode of the diode D, is connected with the ground terminal through the second capacitor C2 and the third capacitor C3 respectively, one end of the first magnetic bead FB1, which is connected with the eighth resistor R8, is connected with the ground terminal through the fourth capacitor C4 and the fifth capacitor C5, respectively, the first inductor L1 and the second inductor L2 are connected with the eighth resistor R8 and the ninth resistor R9 in parallel, and a line between the second magnetic bead FB2 and the vehicle-mounted camera is grounded through an electrostatic protection diode ESD.
Furthermore, the circuit also comprises an alarm circuit which is connected with the control chip and is used for alarming when the level detection pin detects a low level.
After the technical scheme is adopted, the embodiment of the utility model provides an at least, following beneficial effect has: the embodiment of the utility model discloses through adopting first triode Q1, second triode Q2, third triode Q3, MOS pipe Q4 and control chip to cooperate respectively, when the current value of external power source input is in predetermined threshold value scope, make second triode Q2 switch on by the enable pin output high level of control chip, and then make MOS pipe Q4 also switch on, external power source can flow through MOS pipe Q4 and supply power for the vehicle-mounted camera, and when the current of external power source input exceeded predetermined threshold value, first triode Q1 will correspondingly switch on, make third triode Q3 also switch on thereupon, because third triode Q3 input connects the input of second triode Q2 and with output ground connection, and make the input of second triode Q2 can't obtain high level and can't switch on, and then also make MOS pipe Q4 correspondingly cut off, thereby disconnect the circuit that external power source supplied power to the vehicle-mounted camera, the vehicle-mounted camera is effectively protected; the whole overcurrent protection circuit adopts few circuit elements and is simple in structure, and the production cost is effectively reduced.
Drawings
Fig. 1 is a circuit diagram of an optional embodiment of the over-current protection circuit of the vehicle-mounted camera.
Detailed Description
The present application will now be described in further detail with reference to the accompanying drawings and specific examples. It is to be understood that the following illustrative embodiments and description are only intended to illustrate the present invention, and are not intended to limit the present invention, and features in the embodiments and examples may be combined with each other in the present application without conflict.
As shown in fig. 1, an optional embodiment of the present invention provides an over-current protection circuit for a vehicle-mounted camera, which is connected between an external power source 1 and a vehicle-mounted camera 3, wherein the circuit includes a first transistor Q1, a second transistor Q2, a third transistor Q3, a MOS transistor Q4 and a control chip 5 for controlling the operating state of the second transistor Q2, the control chip 5 includes a voltage input pin 50 connected to the external power source 1 for obtaining power supply, a level detection pin 52 connected to an input end of the third transistor Q3, and an enable pin 54 connected to a control end of the second transistor Q2 and outputting a high level by default and stopping outputting the high level when the level detection pin 52 detects a low level, wherein:
the input end of the first triode Q1 and the input end of the MOS transistor Q4 are both connected to the external power supply 1, the input end and the control end of the first triode Q1 are connected through a first resistor R1, and the output end of the first triode Q1 is connected to the control end of a third triode Q3 and is also grounded through a second resistor R2;
an output end of the second transistor Q2 and an output end of the third transistor Q3 are both grounded, an input end of the second transistor Q2 is connected to a control end of the MOS transistor Q4, and a control end of the second transistor Q2 is respectively connected to the enable pin 54 and an input end of the third transistor Q3;
the input end and the control end of the MOS tube Q4 are connected through a second resistor R3, and the output end of the MOS tube Q4 is used as the output end of the overcurrent protection circuit and is connected to the vehicle-mounted camera 3.
The embodiment of the present invention employs the first transistor Q1, the second transistor Q2, the third transistor Q3, the MOS transistor Q4 and the control chip 5 to cooperate with each other, when the current value inputted by the external power supply 1 is within the predetermined threshold range, the enable pin 54 of the control chip 5 outputs a high level to turn on the second transistor Q2, so as to turn on the MOS transistor Q4, the external power supply 1 can supply power to the vehicle-mounted camera 3 through the MOS transistor Q4, and when the current inputted by the external power supply 1 exceeds the predetermined threshold, the first transistor Q1 will be correspondingly turned on, so as to turn on the third transistor Q3, because the input end of the third transistor Q3 is connected to the input end of the second transistor Q2 and grounded through the output end, so that the input end of the second transistor Q2 can not obtain a high level and can not be turned on, and further the MOS transistor Q4 is correspondingly turned off, thereby disconnecting the circuit supplying power from the external power supply 1 to the vehicle-mounted camera 3, the vehicle-mounted camera 3 is effectively protected; the whole overcurrent protection circuit adopts few circuit elements and is simple in structure, and the production cost is effectively reduced.
In a specific embodiment of the present invention, the first triode Q1 is of the MMBT3906 type, the second triode Q2 is of the BCW66GLT1G type, the third triode Q3 is of the BCW66GLT1G type, and the MOS transistor Q4 is of the AO3401 type, it can be understood that the first triode Q1 is of the PNP type according to the types of the triode and the MOS transistor Q4, and the input terminal, the output terminal, and the control terminal are the emitter, the collector, and the base, respectively; the second triode Q2 and the third triode Q3 are both NPN type triodes, and the input end, the output end and the control end of the second triode Q2 and the third triode Q3 are respectively a collector, an emitter and a base; the MOS transistor Q4 is a PMOS transistor, and its input terminal, output terminal and control terminal are a source, a drain and a gate, respectively. It can be understood that, in practical applications, the respective input terminal, output terminal and control terminal can also be flexibly determined according to the type of the adopted triode and MOS transistor.
In an optional embodiment of the present invention, the enable pin 54 is switched to output low when the level detection pin 50 detects low level. In this embodiment, the enable pin 54 is switched to output a low level when the level detection pin 50 detects a low level, on one hand, after the input end of the third triode Q3 outputs a low level, the control end of the second triode Q2 inputs a low level, the second triode Q2 is cut off, and the input end of the second triode Q2 is at a high level, which results in the MOS transistor Q4 being turned off, on the other hand, when the input end of the current detection pin 52 is at a low level, which results in the enable pin 50 outputting a low level, the MOS transistor Q4 is also turned off, the external power supply 1 cannot supply power to the vehicle-mounted camera 3, and the overcurrent current of the external power supply 1 cannot be output to the vehicle-mounted camera 3, thereby achieving dual protection.
In yet another optional embodiment of the present invention, the external power source 1 is further connected to the input terminal of the MOS transistor Q4 through a fourth resistor R4. This embodiment is through setting up fourth resistance R4 for external power source 1's input voltage produces the pressure drop at fourth resistance R4, and the resistance value of adjustment fourth resistance R4 that can be nimble is in order to change the utility model discloses the overcurrent value that overcurrent protection circuit restricted.
In yet another alternative embodiment of the present invention, the output terminal of the first transistor Q1 is connected to the control terminal of the third transistor Q3 through a fifth resistor R5. In the embodiment, by providing the fifth resistor R5, a voltage drop is also generated in the fifth resistor R5 during an overcurrent condition, so that the third transistor Q3 is protected.
In another optional embodiment of the present invention, a sixth resistor R6 and a seventh resistor R7 are connected in series between the control terminal of the second transistor Q2 and the enable pin 54, and the input terminal of the third transistor Q3 is connected to a line between the sixth resistor R6 and the seventh resistor R7. The sixth resistor R6 and the seventh resistor R7 are provided in this embodiment, so that the third transistor Q3 and the control chip 5 can be effectively protected.
In yet another optional embodiment of the present invention, the output terminal of the MOS transistor Q4 is further grounded through the first capacitor C1. This embodiment is through setting up first electric capacity C1, and the clutter composition of preliminary filtering external power supply 1 output to in-vehicle camera 3 reduces the interference, improves the stability of circuit.
In another optional embodiment of the present invention, the circuit further includes a diode D having an anode connected to the output terminal of the MOS transistor Q4 and a cathode connected to the vehicle-mounted camera 3. The embodiment also prevents the reverse flow of current by arranging the diode D, burns out the circuit and improves the reliability of the circuit.
In another optional embodiment of the present invention, a filter circuit 7 is connected between the cathode of the diode D and the vehicle-mounted camera 3. This embodiment is through setting up filter circuit 7 between diode D's negative pole and on-vehicle camera 3, and the noise wave part of further filtering external power supply 1 output current improves the stability of circuit.
In an optional embodiment of the present invention, the filter circuit 7 includes: a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a first magnetic bead FB1, a second magnetic bead FB2, a first inductor L1, a second inductor L2, an eighth resistor R8, a ninth resistor R9 and an ESD protection diode ESD, wherein, the cathode of the diode D is connected to the vehicle-mounted camera 3 through a serial connection body of the first magnetic bead FB1, the eighth resistor R8, the ninth resistor R9 and the second magnetic bead FB2 in sequence, one end of the first magnetic bead FB1, which is connected with the cathode of the diode D, is connected with the ground terminal through the second capacitor C2 and the third capacitor C3 respectively, one end of the first magnetic bead FB1, which is connected with the eighth resistor R8, is connected with the ground terminal through the fourth capacitor C4 and the fifth capacitor C5, respectively, the first inductor L1 and the second inductor L2 are connected with the eighth resistor R8 and the ninth resistor R9 in parallel, and a line between the second magnetic bead FB2 and the vehicle-mounted camera 3 is grounded through an anti-static protection diode ESD. In the embodiment, the second-order filter circuit is composed of the second capacitor C2, the third capacitor C3, the fourth capacitor C4, the fifth capacitor C5, the first magnetic bead FB1, the second magnetic bead FB2, the first inductor L1, the second inductor L2, the eighth resistor R8 and the ninth resistor R9, so that the filter effect is good, and the interference is reduced; and the anti-static protection diode ESD is arranged, so that the vehicle-mounted camera 3 can be effectively prevented from static electricity, and the interference of static electricity is avoided.
In another optional embodiment of the present invention, the circuit further comprises an alarm circuit 8 connected to the control chip 5 for alarming when the level detection pin 52 detects a low level. This embodiment can be through setting up alarm circuit 8 the utility model discloses when overcurrent protection circuit takes place to overflow (level detection pin 52 input low level), effectual warning user. In specific implementation, the alarm circuit 8 may be an LED display circuit, a buzzer circuit, or a display circuit, which is not described in detail herein.
The embodiments of the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, which are only illustrative and not restrictive, and those skilled in the art can make many forms without departing from the spirit and scope of the present invention, and these forms are within the scope of the present invention.
Claims (10)
1. An overcurrent protection circuit of a vehicle-mounted camera is connected between an external power supply and the vehicle-mounted camera, and is characterized in that the circuit comprises a first triode Q1, a second triode Q2, a third triode Q3, a MOS tube Q4 and a control chip for controlling the working state of the second triode Q2, wherein the control chip comprises a voltage input pin connected to the external power supply for obtaining power supply, a level detection pin connected to the input end of the third triode Q3 and an enable pin connected to the control end of the second triode Q2 for outputting a high level by default and stopping outputting the high level when the level detection pin detects a low level, wherein:
the input end of the first triode Q1 and the input end of the MOS transistor Q4 are both connected to the external power supply, the input end and the control end of the first triode Q1 are connected through a first resistor R1, and the output end of the first triode Q1 is connected to the control end of the third triode Q3 and is also grounded through a second resistor R2;
an output end of the second triode Q2 and an output end of the third triode Q3 are both grounded, an input end of the second triode Q2 is connected to a control end of the MOS transistor Q4, and a control end of the second triode Q2 is respectively connected to the enable pin and an input end of the third triode Q3;
the input end and the control end of the MOS tube Q4 are connected through a second resistor R3, and the output end of the MOS tube Q4 is used as the output end of the overcurrent protection circuit and is connected to the vehicle-mounted camera.
2. The over-current protection circuit for vehicle-mounted camera head according to claim 1, wherein the enable pin is switched to output low level when the level detection pin detects low level.
3. The over-current protection circuit of the vehicular camera according to claim 1, wherein the external power supply is further connected to an input terminal of a MOS transistor Q4 through a fourth resistor R4.
4. The over-current protection circuit of the vehicular camera head as claimed in claim 1, wherein the output terminal of the first transistor Q1 is connected to the control terminal of the third transistor Q3 through a fifth resistor R5.
5. The over-current protection circuit of the vehicular camera head as claimed in claim 1, wherein a sixth resistor R6 and a seventh resistor R7 are connected in series between the control terminal of the second transistor Q2 and the enable pin, and the input terminal of the third transistor Q3 is connected to a line between the sixth resistor R6 and the seventh resistor R7.
6. The over-current protection circuit of the vehicular camera according to claim 1, wherein the output terminal of the MOS transistor Q4 is further grounded through a first capacitor C1.
7. The over-current protection circuit of the vehicular camera according to claim 1, further comprising a diode D having an anode connected to the output terminal of the MOS transistor Q4 and a cathode connected to the vehicular camera.
8. The overcurrent protection circuit of the vehicle-mounted camera according to claim 7, wherein a filter circuit is connected between a cathode of the diode D and the vehicle-mounted camera.
9. The overcurrent protection circuit for a vehicle-mounted camera according to claim 8, wherein the filter circuit comprises: a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a first magnetic bead FB1, a second magnetic bead FB2, a first inductor L1, a second inductor L2, an eighth resistor R8, a ninth resistor R9 and an ESD protection diode ESD, wherein the cathode of the diode D is connected to the vehicle-mounted camera through a serial connection body of the first magnetic bead FB1, the eighth resistor R8, the ninth resistor R9 and the second magnetic bead FB2 in sequence, one end of the first magnetic bead FB1, which is connected with the cathode of the diode D, is connected with the ground terminal through the second capacitor C2 and the third capacitor C3 respectively, one end of the first magnetic bead FB1, which is connected with the eighth resistor R8, is connected with the ground terminal through the fourth capacitor C4 and the fifth capacitor C5, respectively, the first inductor L1 and the second inductor L2 are connected with the eighth resistor R8 and the ninth resistor R9 in parallel, and a line between the second magnetic bead FB2 and the vehicle-mounted camera is grounded through an electrostatic protection diode ESD.
10. The over-current protection circuit of the vehicular camera according to claim 1, further comprising an alarm circuit connected to the control chip for alarming when the level detection pin detects a low level.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921747706.9U CN210838923U (en) | 2019-10-17 | 2019-10-17 | Over-current protection circuit of vehicle-mounted camera |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201921747706.9U CN210838923U (en) | 2019-10-17 | 2019-10-17 | Over-current protection circuit of vehicle-mounted camera |
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| CN210838923U true CN210838923U (en) | 2020-06-23 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110620368A (en) * | 2019-10-17 | 2019-12-27 | 深圳市豪恩汽车电子装备股份有限公司 | Over-current protection circuit of vehicle-mounted camera |
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2019
- 2019-10-17 CN CN201921747706.9U patent/CN210838923U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110620368A (en) * | 2019-10-17 | 2019-12-27 | 深圳市豪恩汽车电子装备股份有限公司 | Over-current protection circuit of vehicle-mounted camera |
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