TW202411096A - Anti-static electricity protection circuit structure for network signal bus of electronic control unit - Google Patents

Abstract

A anti-static electricity protection circuit structure is applied for network signal bus of an electronic control unit, and includes a CAN Bus protection circuit and a LIN bus protection circuit. The CAN Bus protection circuit is electrically connected an ECU through a CAN bus signal transceiver, and electrically connected the CAN bus signal transceiver, a common-mode inductance, and a first TVS diode in sequence and then grounded. The LIN bus protection circuit is electrically connected to a LIN bus signal transmission circuit, which is electrically connected a LIN bus signal input end, a LIN bus signal transceiver and the ECU in sequence. An end of a second TVS diode is connected to a contact of LIN bus signal transmission circuit between the LIN bus signal input end and the LIN bus signal transceiver, and the other end of the second TVS diode is grounded.

Description

Anti-static protection circuit structure for network signal bus of electronic control unit

The present invention relates to an anti-static protection circuit structure, and more particularly to an anti-static protection circuit structure for a network signal bus of an electronic control unit.

Static electricity is a static charge group that temporarily or permanently gathers on a substance and is blocked by the surrounding high-resistance medium, so it cannot flow out of the substance. Once these charge groups accumulate in large quantities, the potential energy increases, and the isolation conditions of the high-resistance medium change, such as when a conductive medium comes close to the substance, air discharge or contact discharge may occur, causing the charge accumulated on the substance to be released to another substance through the conductive medium.

On the other hand, most general vehicles have electronic control units (ECU) installed in the vehicle (such as vehicle computers or their peripheral control devices). Since most vehicles are covered by metal shells, the metal shielding effect provides a certain degree of protection for the electronic devices embedded in the vehicle. However, most tires are made of insulating rubber. When the vehicle body receives the charge released from other substances in the environment, the charge accumulated in the metal shell cannot be truly grounded through the rubber tires to further flow to the ground. Therefore, a large amount of charge may still accumulate and remain on the metal shell.

Once a user's body or an item (such as a key) comes into contact with the metal shell of a vehicle (such as the body, door, or keyhole), a large amount of charge accumulated on the metal shell may flow to the user's body or the item. When the user or the item he or she carries enters the vehicle and approaches or touches the ECU, it may discharge the ECU.

As more and more electronic control units (ECUs) installed in cars are equipped with circuit buses and devices for transmitting network signals, such as the Control Area Network Bus (CAN Bus) and the Local Interconnect Network Bus (LIN Bus), once the above-mentioned charge is released to the ECU, it may cause distortion of the signals transmitted by the CAN Bus and LIN Bus, or even damage important devices (such as ECU, CAN Bus signal transceiver and LIN Bus signal transceiver), making it impossible to continue to transmit network signals normally.

In order to test the ability of ECU devices to withstand static electricity when powered on, the test specification specified in ISO 10605 is widely used among the existing electrostatic discharge (ESD) test specifications. In the ISO 10605 test specification, an ESD test environment is first constructed and the temperature in the test environment is maintained at (23 3)℃, and maintain the relative humidity at 20% to 40%. Then place a probe in the gap of each exposed surface to perform air discharge (using air as the medium instead of direct contact) and contact discharge on the internal space of the ECU device, so as to check whether the internal components or circuits are damaged or malfunctioning after discharge, and use this as the basis for judging the anti-static ability of the ECU device.

In view of the fact that in the prior art, there is generally a lack of appropriate protection circuits to protect the network signal bus (including CAN Bus and LIN Bus) and related devices (such as ECU, CAN Bus signal transceiver and LIN Bus signal transceiver) in the ECU device. As a result, once static electricity is released to the ECU device, it will most affect the network signal transmission function. Therefore, the main purpose of the present invention is to provide a technology to protect the network signal bus (including CAN Bus and LIN Bus) and related devices, so that it can withstand a larger amount of static electricity without affecting its network signal transmission function.

The present invention solves the problems of the prior art by adopting a necessary technical means to provide an anti-static protection circuit structure (hereinafter referred to as "protection circuit structure") for the network signal bus of the electronic control unit. The protection circuit structure includes a control area network bus (Control Area Network Bus; CAN Bus) anti-static protection circuit and a local interconnect network bus (Local Interconnect Network Bus; LIN Bus) anti-static protection circuit.

The CAN Bus anti-static protection circuit is electrically connected to an electronic control unit (ECU) via a CAN Bus signal transceiver, and includes a high voltage level protection branch circuit and a low voltage level protection branch circuit. The high voltage level protection branch circuit is electrically connected from a high potential pin (CANH) of the CAN Bus signal transceiver to a common mode inductor and a first transient voltage suppressor (TVS) diode in sequence and then to ground. The low voltage level protection branch circuit is electrically connected from a low potential pin (CANL) of the CAN Bus signal transceiver to a common mode inductor and a first TVS diode in sequence and then to ground.

The LIN Bus anti-static protection circuit is electrically connected to a LIN Bus signal transmission circuit. The LIN Bus signal transmission circuit is electrically connected to the ECU from a LIN Bus signal input terminal through a LIN Bus signal transceiver in sequence. The LIN Bus anti-static protection circuit includes a second TVS diode. One end of the second TVS diode is electrically connected between the LIN Bus signal input terminal and the LIN Bus signal transceiver, and the other end of the second TVS diode is grounded.

Based on the above necessary technical means, the best auxiliary technical means are derived. The best CAN Bus signal transceiver can be TAJ1040 chip, the LIN Bus signal transceiver is TAJ1027 chip, and the common mode inductor is ACT45B series common mode inductor. Regarding the anti-static ability, the best air discharge voltage and contact discharge voltage that the first TVS diode can withstand are both 30kV, and the air discharge voltage and contact discharge voltage that the second TVS diode can withstand are 15kV and 8kV respectively.

As mentioned above, in the anti-static protection circuit structure of the network signal bus of the electronic control unit provided by the present invention, a CAN Bus anti-static protection circuit and a LIN Bus anti-static protection circuit are additionally electrically connected after the CAN Bus signal transceiver and in the LIN Bus signal transmission circuit, and a first TVS diode and a second TVS diode are respectively set in the CAN Bus anti-static protection circuit and the LIN Bus anti-static protection circuit. Among them, since the CAN Bus transmits a differential signal, a common mode inductor is additionally set. By means of the above means, the electrostatic tolerance of the network signal bus (including CAN Bus and LIN Bus) can be significantly improved, so that its related devices (such as ECU, CAN Bus signal transceiver and LIN Bus signal transceiver) can be protected and less prone to damage.

The anti-static protection circuit structure of the electronic device provided by the present invention can be widely used to protect the network signal bus and related components of various electronic control units. In the replacement selection of equivalent components or equivalent circuits of related components, various local adjustments and improvements can be made accordingly, and the combination implementation methods are too numerous to list, so they will not be described one by one here, and only one of the better implementation examples will be listed for specific explanation. In addition, the figures in each implementation example are all in a very simplified form, which is only used to conveniently and clearly assist in explaining the purpose and effect of the implementation example of the present invention.

Please refer to the first figure, which is a functional block diagram of an anti-static protection circuit structure for a network signal bus of an electronic control unit provided by the present invention. As shown in the first figure, an anti-static protection circuit structure for a network signal bus of an electronic control unit (hereinafter referred to as "protection circuit structure") 100 includes a control area network bus (Control Area Network Bus; CAN Bus) anti-static protection circuit (hereinafter referred to as "CAN Bus protection circuit") 1 and a local interconnect network bus (Local Interconnect Network Bus; LIN Bus) anti-static protection circuit (hereinafter referred to as "LIN Bus protection circuit") 2.

The CAN Bus protection circuit 1 is electrically connected to an electronic control unit (ECU) 300 via a CAN Bus signal transceiver 200, and includes a common mode inductor 11, a first TVS diode 12, a high voltage level protection branch circuit HVP, and a low voltage level protection branch circuit LVP. The LIN Bus protection circuit 2 is electrically connected to a LIN Bus signal transmission circuit LB, and includes a second TVS diode 21. The LIN Bus signal transmission circuit LB is electrically connected to the ECU 300 from a LIN Bus signal input terminal 400 via a LIN Bus signal transceiver 500.

Please refer to the first and second figures together, wherein the second figure is a circuit diagram showing the CAN Bus protection circuit and peripheral related circuits and devices in a preferred embodiment of the present invention. As shown in the first and second figures, since the CAN Bus signal is a differential signal, the CAN Bus signal transceiver 200 includes a high potential pin CANH and a low potential pin CANL.

The high voltage level protection branch circuit HVP is connected to the common mode inductor 11 and the first TVS diode 12 in sequence from the high potential pin CANH of the CAN Bus signal transceiver 200 and then to ground. Similarly, the low voltage level protection branch circuit LVP is connected to the common mode inductor 11 and the first TVS diode 12 in sequence from the low potential pin CANL of the CAN Bus signal transceiver 200 and then to ground.

Preferably, the CAN Bus signal transceiver 200 can be a TAJ1040 chip. The air discharge voltage and contact discharge voltage that the first TVS diode can withstand are both 30kV. The common mode inductor is an ACT45B series common mode inductor.

Please refer to the first and third figures together, wherein the third figure is a circuit diagram showing the LIN Bus protection circuit and peripheral related circuits and devices in the preferred embodiment of the present invention. As shown in the first and third figures, the LIN Bus signal transceiver 500 includes a LIN Bus signal pin (i.e., the pin labeled LIN inside the component 500 in the third figure), a LIN Bus signal sending pin (i.e., the pin labeled TXD inside the component 500 in the third figure) and a LIN Bus signal receiving pin (i.e., the pin labeled RXD inside the component 500 in the third figure). The LIN Bus signal transmission circuit LB is electrically connected to the LIN Bus signal transceiver 500 via a LIN Bus signal pin from the LIN Bus signal input terminal 400, and is further electrically connected to the ECU 300 via a LIN Bus signal sending pin and a LIN Bus signal receiving pin.

One end of the second TVS diode 21 is electrically connected between the LIN Bus signal input terminal 400 and the LIN Bus signal transceiver 500, and the other end of the second TVS diode 21 is grounded. Preferably, the LIN Bus signal transceiver can be a TAJ1027 chip, and the air discharge voltage and contact discharge voltage that the second TVS diode can withstand are 15kV and 8kV respectively.

The overall anti-static capability of the network signal bus of ECU 300 is determined by the stability of CAN Bus signal transmission when the high potential pin CANH and the low potential pin CANL are subject to electrostatic interference or impact, and the stability of LIN Bus signal transmission when the LIN Bus signal pin (i.e., the pin marked LIN inside the component 500 in the third figure) is subject to electrostatic interference or impact.

In addition, according to the ISO 10605 test specification, during the operation of the ECU 300, the high potential pin CANH, the low potential pin CANL, the LIN Bus signal pin and the gap of the housing will be released by contact discharge. 4kV to 8kV static electricity is released by air discharge 4kV to 25kV static electricity; therefore, directly or indirectly connecting the high potential pin CANH, low potential pin CANL, LIN Bus signal pin, etc. to the protection circuit can provide direct and effective protection effect. Through the above means, it is obvious that the static electricity tolerance of the network signal bus (including CAN Bus and LIN Bus) can be greatly improved, so that its related devices (such as ECU 300, CAN Bus signal transceiver 200 and LIN Bus signal transceiver 500) can be protected and less prone to damage.

In summary, the above-mentioned means can significantly improve the electrostatic tolerance of the network signal bus (including CAN Bus and LIN Bus), so that its related devices (such as ECU 300, CAN Bus signal transceiver 200 and LIN Bus signal transceiver 500) can be protected and less prone to damage.

The above detailed description of the preferred specific embodiments is intended to more clearly describe the features and spirit of the present invention, but is not intended to limit the scope of the present invention by the preferred specific embodiments disclosed above. On the contrary, the purpose is to cover various changes and arrangements with equivalents within the scope of the patent application for the present invention.

100: Protection circuit structure 200: CANBus signal transceiver 300: ECU 400: LINBus signal input terminal 500: LINBus signal transceiver 1: CANBus (anti-static) protection circuit 11: Common mode inductor 12: First TVS diode 2: LINBus (anti-static) protection circuit 21: Second TVS diode HVP: High voltage level protection branch circuit LVP: Low voltage level protection branch circuit LB: LINBus signal transmission circuit CANH: High potential pin CANL: Low potential pin

The first figure is a functional block diagram of an anti-static protection circuit structure for a network signal bus of an electronic control unit provided by the present invention; The second figure is a circuit diagram of a CAN Bus protection circuit and peripheral related circuits and devices in a preferred embodiment of the present invention; and The third figure is a circuit diagram of a LIN Bus protection circuit and peripheral related circuits and devices in a preferred embodiment of the present invention.

100: Protection circuit structure

200:CANBus signal transceiver

300:ECU

400:LINBus signal input terminal

500:LINBus signal transceiver

1: CANBus (anti-static) protection circuit

11: Common mode inductor

12: First TVS diode

2:LINBus (anti-static) protection circuit

21: Second TVS diode

HVP: High voltage level protection branch circuit

LVP: low voltage protection branch circuit

LB:LINBus signal transmission circuit

Claims (6)

An anti-static protection circuit structure for a network signal bus of an electronic control unit, comprising: A control area network bus (CAN Bus) anti-static protection circuit, which is electrically connected to an electronic control unit (ECU) via a CAN Bus signal transceiver, and also comprising: A high voltage level protection branch circuit, which is electrically connected from a high potential pin of the CAN Bus signal transceiver to a common mode inductor and a first transient voltage suppressor (TVS) diode in sequence and then to ground; and A low voltage level protection branch circuit, which is electrically connected from a low potential pin of the CAN Bus signal transceiver to the common mode inductor and the first TVS diode in sequence and then to ground; and A local interconnect network bus (Local Interconnect Network Bus) The anti-static protection circuit of the LIN Bus (LIN Bus) is electrically connected to a LIN Bus signal transmission circuit, which is electrically connected to the ECU from a LIN Bus signal input terminal through a LIN Bus signal transceiver in sequence. The LIN Bus anti-static protection circuit includes a second TVS diode, one end of which is electrically connected between the LIN Bus signal input terminal and the LIN Bus signal transceiver, and the other end of which is grounded. An anti-static protection circuit structure for a network signal bus of an electronic control unit as described in claim 1, wherein the CAN Bus signal transceiver is a TAJ1040 chip. An anti-static protection circuit structure for a network signal bus of an electronic control unit as described in claim 1, wherein the LIN Bus signal transceiver is a TAJ1027 chip. As described in claim 1, the anti-static protection circuit structure for the network signal bus of the electronic control unit, wherein the air discharge voltage and contact discharge voltage that the first TVS diode can withstand are both 30kV. As described in claim 1, the anti-static protection circuit structure for the network signal bus of the electronic control unit, wherein the air discharge voltage and contact discharge voltage that the second TVS diode can withstand are 15kV and 8kV respectively. An anti-static protection circuit structure for a network signal bus of an electronic control unit as described in claim 1, wherein the common-mode inductor is an ACT45B series common-mode inductor.

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