CN107611951B - Protection circuit of automobile bus communication line - Google Patents
Protection circuit of automobile bus communication line Download PDFInfo
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- CN107611951B CN107611951B CN201711002146.XA CN201711002146A CN107611951B CN 107611951 B CN107611951 B CN 107611951B CN 201711002146 A CN201711002146 A CN 201711002146A CN 107611951 B CN107611951 B CN 107611951B
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Abstract
The invention discloses a protection circuit of an automobile bus communication line, which comprises a communication interface circuit, an interface protection circuit and a protocol configuration matrix circuit, wherein the signal output end of the communication interface circuit is connected with the input end of the communication interface protection circuit, and the output end of the communication interface protection circuit is connected with the input end of the protocol configuration matrix circuit. The invention provides a protective circuit of an automobile bus communication line, which is used for real-time overcurrent protection and avoids the problems of low PTC reaction speed, incomplete protection and incompleteness; the invention has the advantages of simple circuit structure, small occupied space of devices, real-time, rapid and complete protection and low cost.
Description
Technical Field
The invention relates to the technical field of protection circuits, in particular to a protection circuit of an automobile bus communication line.
Background
Since the 80 th 20 th century, automobiles entered the ECU (electronic Control unit) Control period, automobile manufacturers, represented by the united states three major automobile company, began to monitor automobile Control systems with ECUs. However, the ECUs and the fault diagnosis devices of each manufacturer are developed by each automobile manufacturer, and the diagnosis interfaces and the communication modes are different from each other and cannot be used commonly.
Therefore, various comprehensive diagnosis devices are developed in the automobile aftermarket, and the protocol type of the electric control system of the automobile is analyzed and judged by performing protocol scanning on each communication pin of the automobile OBD-16 diagnosis seat, so that the self-service diagnosis of various electric control systems of multiple automobile systems is realized. However, as each automobile manufacturer OBD-16 diagnosis seat defines different use times for undefined pins of the standard specification of the second generation On-Board Diagnostic system (OBD-II) (On-Board Diagnostic II), when the comprehensive diagnosis device is connected and diagnosed with the automobile OBD-16 diagnosis seat, circuits with large electrical characteristic differences are inevitably connected with each other, so that the diagnosis device and the communication circuit of the electronic control system of the ECU have damage risks of overcurrent and overvoltage, which requires that a reliable protection circuit is necessary when the comprehensive diagnosis device is connected to the automobile OBD-16 diagnosis seat to ensure the safety of the device and the automobile ECU, especially the safety of the automobile ECU.
The current comprehensive diagnostic devices in the market basically adopt PTC (self-recovery fuse) and TVS (Transient Voltage Suppressor) protection circuits on each communication line. This brings about the following disadvantages.
1. Since PTC is a temperature sensitive device, its reaction time is slow and therefore its protection is incomplete.
2. The PTC used on each communication line has high cost, occupies large area of the circuit board and forms certain obstacle to the miniaturization of equipment.
Disclosure of Invention
The present invention is directed to solving the above problems and providing a protection circuit for an automotive bus communication line.
The invention realizes the purpose through the following technical scheme:
the invention comprises a communication interface circuit, an interface protection circuit and a protocol configuration matrix circuit, wherein the signal output end of the communication interface circuit is connected with the input end of the communication interface protection circuit, and the output end of the communication interface protection circuit is connected with the input end of the protocol configuration matrix circuit.
Preferably, the communication interface circuit includes a first clamping triode group and a second clamping triode group, the first clamping triode group includes a first triode, a first current-limiting isolation resistor and a first sampling resistor, a base of the first triode is connected in series with the first current-limiting isolation resistor, a collector of the first triode is connected in series with the first sampling resistor, the second clamping triode group includes a second triode, a second current-limiting isolation resistor and a second sampling resistor, a base of the second triode is connected in series with the second current-limiting isolation resistor, and a collector of the second triode is connected in series with the second sampling resistor.
Preferably, the protection circuit for the bus communication line of the vehicle is characterized in that: the LOGIC-end of the communication interface circuit and the ECU end of the OBD-16 diagnosis seat are connected with a low-impedance load, when a signal on the left side of the first sampling resistor is high level, the field effect tube is cut off, the LOGIC-end of the communication interface circuit is connected with low level through the first resistor, and the circuit is safe and normal; when a signal on the left side of the first sampling resistor is at a low level, the field effect transistor is in saturation conduction, a large current flows through the first sampling resistor, when the current reaches 110-120 mA, the voltage drop on the first sampling resistor is 0.3V, the first triode is in saturation conduction, the right side of the first current-limiting isolation resistor is clamped to be at a high level, the field effect transistor is cut off, the current of the communication interface circuit is limited to be zero, and the safety of circuit devices is guaranteed.
Preferably, the protection circuit for the bus communication line of the vehicle is characterized in that: the DTS end of the communication interface circuit and the ECU end of the OBD-16 diagnosis seat are accessed to Vbat; when the signal on the left side of the second current limiting isolation resistor is at a low level, the VMOS field effect transistor is cut off, the DTS end of the communication interface circuit is connected to a high level through the second resistor, and the circuit is safe and normal; when the signal on the left side of the second current-limiting isolation resistor is at a high level, the VMOS field effect transistor is saturated and conducted, large current flows through the second sampling resistor, when the current reaches about 120mA, the voltage drop on the first sampling resistor is about 0.6V, the second triode is saturated and conducted, the right side of the second current-limiting isolation resistor is clamped to be at a low level, the VMOS field effect transistor is cut off, the current on the communication interface circuit is limited to be zero, and the safety of circuit devices is ensured.
The invention has the beneficial effects that:
the invention provides a protective circuit of an automobile bus communication line, which is used for real-time overcurrent protection and avoids the problems of low PTC reaction speed, incomplete protection and incompleteness; the invention has the advantages of simple circuit structure, small occupied space of devices, real-time, rapid and complete protection and low cost.
Drawings
FIG. 1 is a circuit diagram of a protection circuit for a bus communication line of a vehicle according to the present invention;
fig. 2 is a circuit diagram of a communication interface circuit according to the present invention.
Detailed Description
The invention will be further described with reference to the accompanying drawings in which:
as shown in fig. 1: the invention comprises a communication interface circuit, an interface protection circuit and a protocol configuration matrix circuit, wherein the signal output end of the communication interface circuit is connected with the signal input end of the interface protection circuit, and the output end of the interface protection circuit is connected with the signal input end of the protocol configuration matrix circuit.
As shown in fig. 2, the communication interface circuit includes a first clamping triode group and a second clamping triode group, the first clamping triode group includes a first triode Q17, a first sampling resistor R132 and a first current-limiting isolation resistor R143, the base of the first triode Q17 is connected in series with the first sampling resistor R132, the collector of the first triode Q17 is connected in series with the first current-limiting isolation resistor R143, the second clamping triode group includes a second triode Q14, a second sampling resistor R133 and a second current-limiting isolation resistor R138, the base of the second triode Q14 is connected in series with the second sampling resistor R133, the collector of the second triode Q14 is connected in series with the second current-limiting isolation resistor R138, the LOGIC-end of the communication interface circuit and the ECU-end of the OBD-16 diagnostic socket are connected to form a load, when the left signal of the first current-limiting isolation resistor R143 is high level, the fet U16 is turned off, the LOGIC-end of the communication interface circuit is connected to low level through the first resistor R144, the circuit is safe and normal; when a signal on the left side of the first current-limiting isolation resistor R143 is at a low level, the field-effect tube U16 is in saturated conduction, large current flows through the first sampling resistor R132, when the current reaches 110-120 mA, the voltage drop on the first sampling resistor R132 is 0.3V, the first triode Q17 is in saturated conduction, the right side of the first current-limiting isolation resistor R143 is clamped to be at a high level, the field-effect tube U16 is cut off, the current of the communication interface circuit is limited to be zero, the safety of a circuit device is ensured, and the Vbat is connected between the DTS end of the communication interface circuit and the ECU end of the OBD-16 diagnosis seat; when a signal on the left side of the second current limiting isolation resistor R138 is at a low level, the VMOS field effect transistor U15 is cut off, the DTS end of the communication interface circuit is connected to a high level through the second resistor R137, and the circuit is safe and normal; when a signal on the left side of the second current-limiting isolation resistor R138 is at a high level, the VMOS field-effect tube U15 is in saturated conduction, a large current flows through the second sampling resistor R133, when the current reaches about 120mA, the voltage drop on the second sampling resistor R133 is about 0.6V, the second triode Q14 is in saturated conduction, the right side of the second current-limiting isolation resistor R138 is clamped to be at a low level, the VMOS field-effect tube U15 is cut off, the current on the communication interface circuit is limited to be zero, and the safety of circuit devices is ensured.
In conclusion, the invention provides a protection circuit of an automobile bus communication line, which is used for real-time overcurrent protection and avoids the problems of low PTC reaction speed, incomplete protection and incompleteness; the invention has the advantages of simple circuit structure, small occupied space of devices, real-time, rapid and complete protection and low cost.
As will be apparent to those skilled in the art, many modifications can be made to the invention without departing from the spirit and scope thereof, and it is intended that the present invention cover all modifications and equivalents of the embodiments of the invention covered by the appended claims.
Claims (2)
1. A protection circuit of an automobile bus communication line is characterized by comprising a communication interface circuit, an interface protection circuit and a protocol configuration matrix circuit, wherein a signal output end of the communication interface circuit is connected with an input end of the interface protection circuit, and an output end of the interface protection circuit is connected with an input end of the protocol configuration matrix circuit;
the communication interface circuit comprises a first clamping triode group and a second clamping triode group, the first clamping triode group comprises a first triode, a first current-limiting isolation resistor and a first sampling resistor, the base of the first triode is connected with the first current-limiting isolation resistor in series, the collector of the first triode is connected with the first sampling resistor in series, the second clamping triode group comprises a second triode, a second current-limiting isolation resistor and a second sampling resistor, the base of the second triode is connected with the second current-limiting isolation resistor in series, and the collector of the second triode is connected with the second sampling resistor in series;
the LOGIC end of the communication interface circuit is connected with the ECU end of the OBD-16 diagnosis seat through a low-impedance load, when a signal on the left side of the first current-limiting isolation resistor is high level, the field effect tube is cut off, one end of the LOGIC end of the communication interface circuit is connected with low level through the first resistor, and the circuit is safe and normal; when a signal on the left side of the first current-limiting isolation resistor is at a low level, the field effect transistor is in saturation conduction, a large current flows through the first sampling resistor, when the current reaches 110-120 mA, the voltage drop on the first sampling resistor is 0.3V, the first triode is in saturation conduction, the right side of the first current-limiting isolation resistor is clamped to be at a high level, the field effect transistor is cut off, the current of the communication interface circuit is limited to be zero, and the safety of circuit devices is guaranteed.
2. The protection circuit for an automotive bus communication line according to claim 1, characterized in that: the DTS end of the communication interface circuit and the ECU end of the OBD-16 diagnosis seat are accessed to Vbat; when the signal on the left side of the second current limiting isolation resistor is at a low level, the VMOS field effect transistor is cut off, the DTS end of the communication interface circuit is connected to a high level through the second resistor, and the circuit is safe and normal; when the signal on the left side of the second current-limiting isolation resistor is at a high level, the VMOS field effect transistor is saturated and conducted, large current flows through the second sampling resistor, when the current reaches about 120mA, the voltage drop on the second sampling resistor is about 0.6V, the second triode is saturated and conducted, the right side of the second current-limiting isolation resistor is clamped to be at a low level, the VMOS field effect transistor is cut off, the current on the communication interface circuit is limited to be zero, and the safety of circuit devices is ensured.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711002146.XA CN107611951B (en) | 2017-10-24 | 2017-10-24 | Protection circuit of automobile bus communication line |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711002146.XA CN107611951B (en) | 2017-10-24 | 2017-10-24 | Protection circuit of automobile bus communication line |
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| Publication Number | Publication Date |
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| CN107611951A CN107611951A (en) | 2018-01-19 |
| CN107611951B true CN107611951B (en) | 2020-04-07 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201711002146.XA Active CN107611951B (en) | 2017-10-24 | 2017-10-24 | Protection circuit of automobile bus communication line |
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201315646Y (en) * | 2008-12-23 | 2009-09-23 | 深圳创维－Rgb电子有限公司 | Digital audio interface circuit for TV |
| DE102014107748A1 (en) * | 2013-06-03 | 2014-12-04 | Infineon Technologies Ag | Switch-off protection for bus line drivers |
| CN104660247A (en) * | 2015-03-10 | 2015-05-27 | 北京大恒图像视觉有限公司 | Two-way interface circuit |
| CN204720953U (en) * | 2015-06-18 | 2015-10-21 | 深圳市高科润电子有限公司 | Electric vehicle controller hardware current foldback circuit |
| CN105516076A (en) * | 2015-09-23 | 2016-04-20 | 广汽吉奥汽车有限公司 | Unified multi-protocol conversion device |
| CN205186049U (en) * | 2015-08-06 | 2016-04-27 | 四川九洲电器集团有限责任公司 | OBD automobile -mounted terminal |
| CN207339254U (en) * | 2017-10-24 | 2018-05-08 | 深圳市博诺技术有限公司 | A kind of protection circuit of automobile bus communication line |
-
2017
- 2017-10-24 CN CN201711002146.XA patent/CN107611951B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201315646Y (en) * | 2008-12-23 | 2009-09-23 | 深圳创维－Rgb电子有限公司 | Digital audio interface circuit for TV |
| DE102014107748A1 (en) * | 2013-06-03 | 2014-12-04 | Infineon Technologies Ag | Switch-off protection for bus line drivers |
| CN104660247A (en) * | 2015-03-10 | 2015-05-27 | 北京大恒图像视觉有限公司 | Two-way interface circuit |
| CN204720953U (en) * | 2015-06-18 | 2015-10-21 | 深圳市高科润电子有限公司 | Electric vehicle controller hardware current foldback circuit |
| CN205186049U (en) * | 2015-08-06 | 2016-04-27 | 四川九洲电器集团有限责任公司 | OBD automobile -mounted terminal |
| CN105516076A (en) * | 2015-09-23 | 2016-04-20 | 广汽吉奥汽车有限公司 | Unified multi-protocol conversion device |
| CN207339254U (en) * | 2017-10-24 | 2018-05-08 | 深圳市博诺技术有限公司 | A kind of protection circuit of automobile bus communication line |
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| Publication number | Publication date |
|---|---|
| CN107611951A (en) | 2018-01-19 |
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