TCAN1044A-Q1: What is the tolerance of VCANH VCANL and Vdiff of the dominant and recessive status?

1. The high-speed CAN specification requires drivers to output a differential voltage of typically 2 V (with the dominant common-mode voltage between 1.5 V and 3.5 V); receivers are required to treat > 0.9 V as dominant and < 0.5 V as recessive. (The specification can be bought from ISO.)

2. All CAN transceivers that conform to the specification (which is all of them) are interoperable.

Hi Zhiyuan,

1. On the receiving end, V_diff will treat any value > 0.9 V as dominant and < 0.5 V as recessive. so the transmitters are required to produce a v_diff of at least 1.5 V, however in this case I believe it's 2 V. When it comes to the tolerance of VCANH and VCANL, there is a difference between the tolerance for a part to work properly, and a tolerance that will damage the part. For this part, the TCAN1044A, the buses can reach plus or minus 58 volts before being damaged, but the v_diff cannot exceed plus or minus 45 volts without being damaged. That being said, the bus won't function properly at much smaller values. For example, if VCANH is within the limit, but is much higher than VCANL, then it's possible for v_diff to never be less than 0.5 V so that a recessive state can never be reached. Overall, V_diff needs to be able to reach a dominant and recessive state above all else.

2. As long as a CAN transceiver is following ISO11898-2:2016, then it should work with all transceivers following the standard.

Hope this helps,
Zach