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TCAN332: TCAN332 failure from potential ESD event

dax inman
Prodigy 20 points

Part Number: TCAN332

We had 2 instances of TCAN332DR failures.

In the most recent case the CAN transivecr and R33 (60 ohm split term resistor) needed to be replaced. R33 failed open. The TCAN 332 was not functional, Tx from micro being sent correctly, no transmission though to CAN_L and CAN_H. Fixed as soon as TCAN332 was replaced.

When we think the TCAN was damaged, there was a ESD event on a circuit which is in the same harness bundle with CAN_H and CAN_L, but is electrically isolated. 

I took the resistance measurements of the failed part, after removing from PCB. Compared to a virgin part.

TCAN332_impedance.png

Below is the relevant schematic. 

TCAN332.png

 

Are there any concerns with the schematic as shown? specifically in terms of ESD immunity

Given the resistances, i think internally the RX input on the bad TCAN332 failed short. Any ways this could happen?

  • 0
    TI__Guru* 78662 points

    Hi Dax,

    Looks good overall. The main concern would be if the ESD diode is not placed as close as possible to the connector similar to the data sheet's layout recommendation.

    I.e., CMC as close to the IC pin then termination and then the ESD diode close to the connector.

    For this to happen, the abs max or ESD specification ratings were most likely exceeded and would have to double confirm based on your system environment / testing if any possibilities / vulnerabilities for such, thanks.

    Best Regards,

    Michael.