TCAN1043-Q1: question about the Rterm

Hi Sherry,

There aren't any special requirements for the resistors in terms of CAN signaling other than having a proper resistance value (to provide a defined load to the CAN drivers and match the transmission line impedance) and being able to handle the differential voltage amplitude (which is at most the VCC level).

Applications frequently have additional requirements for fault tolerance that could impact the resistor selection, though. For example,  if one of the CAN bus lines were shorted to a battery or ground line, high current could flow through the termination resistances when the CAN bus is dominant. In this case the current would be limited by the transceiver, typically to 100 mA. Other more extreme fault cases could short one side of the resistance to battery and the other to ground. In this case the only thing limiting the current would be the resistance, and so larger power ratings would be needed to ensure the resistance doesn't become damaged in this case.

Regards,

Max

Hey Sherry,

Currently Max is out of the office. I checked with a collegue of mine on what you were asking and as far as we know, we do not have any type of app note discussing termination resistor requirements. My suggestion would be to make sure the resistors you choose are within your level of acceptable tolerance and are rated to an acceptable power rating (take into account fault conditions).

-Bobby