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TCAN1462-Q1: is there a recommend sample point in percentage with different data rate from 1M to 5M?

Part Number: TCAN1462-Q1
Other Parts Discussed in Thread: ESD2CANFD24,

Tool/software:

Hi team,

Customer has several questions that I need to check. 

  1. Customer use Star topology in their system and get problems to improve the signal quality, remove the ringing. For example, with different data rate from 1M to 5M, is there a recommend sample point in percentage? Do we have document for reference? Can this problem solved by software?
  2. Now they use hand-in-hand connection with 5M, Do we have recommend configuration for this?
  3. Customer use ESD2CANFD24 on each node, there are 10*Nodes totally for the transceiver, so 10 ESD Diode on CANH or CANL, it will introduce much  parasitic capacitance, will it reduce the signal quality? If so  how to solve it?

Thanks a lot

Matthew

  • Matthew,

    In general, the rule of thumb is 80% of the bit for a sample point. This can be adjusted based on the network topology and data rate, but this late in the bit will give time for any ringing to settle, and using the TCAN1462-Q1 which has ringing suppression, this should be enough time for the bit to be established across the entire CAN bus for sampling.

    By hand-in-hand do you mean just two nodes point-to-point communicating? 

    Adding capacitance to the CAN bus will cause more delay in each signal, but ESD2CANFD24 was designed with this mind. It has minimal capacitance, so 10 of these on the bus won't be enough to cause delays in CAN communication to the point of errors. In general, it's expected that each node with have these protective components, it's up to the system designer to test and manage the sample point in the controller software to make sure each bit has enough time to reach the entire length of the bus and back so that it can be properly sampled.

    Regards,

    Eric Hackett