With the intelligence of automobiles, the rapid development of electric vehicles and driverless cars, as well as the increasing demand for advanced driver assistance systems in vehicles, the traditional CAN is becoming increasingly inadequate in terms of transmission rate and bandwidth. CAN FD (Controller Area Network Flexible Data-Rate), an upgraded version of the traditional CAN protocol, is gradually replacing the traditional CAN bus in multiple fields due to its high bandwidth (up to 12 Mbps) and large data payload (64 bytes per frame) features. 

CAN FD Interface ESD Protection Scheme

The CAN FD interface requires an effective protection scheme to prevent electrostatic discharge (ESD) and surge interference, ensuring reliable and stable communication. An external protection circuit is installed with ESD protection diodes on the CAN FD bus connector. The ESD circuit can be applied to both CANH and CANL lines to protect the two CAN FD bus lines from damage caused by ESD and other transient phenomena, and to ensure signal integrity. Additionally, a suitable working voltage should be selected to ensure robustness in different environments. The diagram of Shanghai Leimao's CAN FD protection scheme is as follows:

The above-mentioned scheme applies Shanghai Leimao SMC24LVQ and SMC27LVQ for protection. There are two options because the customer selects the one based on the working voltage.

2、Domestic substitution

The SMC24LVQ and SMC27LVQ products launched by Shanghai Lebao can completely replace the ESD2CANFD24 and PESD2CANFD27V-T两款 CAN FD static protection diodes from TI and Nexperia respectively. The parameter comparison table is as follows： 

Comparison of parameters between Leiditech SMC24LVQ and TI's ESD2CANFD24:

Comparison of Parameters between Leiditech SMC27LVQ and Nexperia's PESD2CANFD27V-T

To determine whether an ESD diode can be used as a substitute, the following points should be considered: 

1) Is VRWM close? 

2) Is the anti-static performance close? 

3) Is VBR close? 

4) Is IPP close? 

5) Is CJ close? 

The above parameters in the comparison table are relatively close. Some parameters of the Lebao brand are superior. For example, for SMC27LVQ and IPP 3.5A, they are both greater than 2.5A of PESD2CANFD27V-T, and the VC is lower, and the anti-static capability of 30KV is stronger. 

2. Application Areas

1) Automotive Electronics

l Dynamic Lighting System 

Control multiple-pixel OLED vehicle lights through the CAN FD Light protocol, achieving complex animations and dimming effects (such as tail lights and turn signals). 

Intelligent Driving and Electrification 

Used for transmitting data from ADAS sensors (radar, cameras), battery management system (BMS), and on-board diagnostic (OBD). 

2) Industrial Automation

l Coordinated control of multiple devices: such as high-precision command transmission between industrial robots, PLCs and CNC machines. Conversion from CAN FD to UART protocol enables real-time data exchange and reduces system latency. 

Energy Management: In the new energy energy storage project, the battery pack is connected via the CAN FD interface, and multi-node data is collected at a rate of 5 Mbps. Combined with HyperRAM cache, the processing efficiency is enhanced. 

3) Emerging intelligent vehicles

l Unmanned transportation systems 

The Agicor CAN FD solution integrates GNSS positioning and inertial navigation to ensure reliable communication for logistics AGVs in environments with weak signals such as tunnels. 

In conclusion, CAN FD is rapidly penetrating in automotive lighting, autonomous driving, industrial interconnection, and aircraft transportation. Our key protection choice is to select protective components with low capacitance (< 6pF is preferred) and high ESD rating (> ±15kV) for the best protection. 

Leiditech Electronics is committed to becoming a leading brand in electromagnetic compatibility solutions and component supply, offering products such as ESD, TVS, TSS, GDT, MOV, MOSFET, Zener, and inductors. Leiditech has an experienced R&D team that can provide personalized customization services based on customer needs, offering the best solutions to customers.