This article outlines the voltage tolerance and protection guidelines for CAN transceivers and emphasizes which overvoltage that CAN transceivers can withstand.
APPLICABLE PRODUCTS
CAN-IB100/PCIe, CAN-IB200/PCIe, CAN-IB300/PCI, CAN-IB400/PCI, CAN-IB520/PCIe mini, CAN-IB600/PCIe, USB-to-CAN V2, USB-to-CAN FD, CAN@net NT
QUESTION
Why did the CAN transceiver on my CAN interface board break?
ANSWER
The CAN transceiver can bear an external overvoltage of about +/- 36V on CAN_H and CAN_L referenced to CAN_GND. An external overvoltage more than +/- 36V can destroy the CAN-Transceiver.
The possible causes for an external overvoltage on the CAN bus:
- Electric disturbances on the CAN bus (generated by drives, lightning…)
A shielded CAN cable can reduce the induced electric disturbances. - High differences of the voltage potentials between different CAN nodes, if the CAN_GNDs are not connected with each other. (We recommend connecting CAN_GND of all CAN nodes with each other for compensating electric current, also when using CAN interface boards with galvanic isolation).
- A wrong wiring, that connects CAN with an external power supply (>36V).
- Analyzing a CAN bus system using a CAN interface board, please connect the CAN bus while it is not running to avoid possible ESD problems.