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 get damaged?
ANSWER
The CAN transceiver can tolerate an external overvoltage of approximately ±36 V on CAN_H and CAN_L relative to CAN_GND. An external overvoltage greater than ±36 V can damage the CAN transceiver.
Possible causes of external overvoltage on the CAN bus:
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Electrical disturbances on the CAN bus, caused by drives, frequency converters, lightning, etc.
(A shielded CAN cable with grounded shielding can help reduce these disturbances.)
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Large voltage potential differences between CAN nodes if the CAN_GND lines are not interconnected.
(We recommend connecting CAN_GND of all CAN nodes to allow compensating currents, even when using CAN interface boards with galvanic isolation.)
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Incorrect wiring, where an external power supply (>36 V) is connected to the CAN bus.
Note:
When analyzing a CAN bus system using a CAN interface board, please connect the CAN bus while it is powered off to avoid possible ESD issues.