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TCAN1043-Q1: Input resistance (CANH or CANL) Test condition

Henry Chan
Prodigy 610 points
Part Number: TCAN1043-Q1
Other Parts Discussed in Thread: TCAN1043

Hi Team, 

Our customer is testing Rin input resistance for TCAN1043-Q1 using VCC = VIO = 5V as per datasheet.

They connect a 1000 Ohm resistor to CAN_H or CAN_L pin, using the resistor as a voltage divider to measure Rin.

There test results shows that Rin is outside of the spec.

Please advise if their test method is valid. 

How did TI test Rin?

Thanks

  • 0
    TI__Guru 53555 points

    Hi Henry,

    The recessive state (TXD = 1 or idle) of the transceiver actively biases the CAN bus to Vcc/2, so the input leakage is a bit more complicated than a simple resistance to GND. To best represent what the impact this bias will have on an active system, the input resistance specification is measured without any external components. This is done by applying the +-30V common mode directly to the CAN pins while the transceiver is in a recessive state. Under this condition, the leakage current can be measured directly to get the effective input resistance under normal operating conditions (no parallel resistance). 

    I would recommend that the customer evaluate the newer TCAN1043A in this case if possible. This device uses a new process technology to allow for better long-term supply capabilities and is functionally the same and pin-to-pin compatible with TCAN1043.

    Let me know if you have any more questions. 

    Regards,
    Eric Schott