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TCAN332: TCAN332 Pin'CANL' reduces impedance to GND

user5785150
Prodigy 10 points
Part Number: TCAN332

TCAN332  3.3V power supply, in the process of communication failure, failure mode is bus U7 pin CANL to GND impedance to varying degrees to reduce or even short circuit. Under normal power-on and non-communication conditions, the chip bus pin to ground voltage is 1.8v, after failure, CANL to GND is less than 0.3V. At present, 9pcs chips fail 6pcs in the reappearing experiment.  

  • 0
    TI__Guru 62920 points
    Hello,

    The most common cause of this type of failure is an electrical overstress, either due to a transient condition like an electrostatic discharge or due to a short-circuit to a voltage beyond a pin's absolute maximum rating. Could either of these conditions have occurred prior to the units failing in this application?

    In general TVS diodes are effective for protecting CAN transceivers against transient overstresses. In this case, though, there may be a mismatch in specs - the SMAJ13CA could clamp to voltages as high as ~20 V (beginning to break down around 15 V), while the maximum rating of the CANL of TCAN332 is 14 V. You may want to consider a lower-voltage TVS like SMAJ8.5CA instead. For your reference, here is a blog on TVS selection for interface devices: e2e.ti.com/.../how-to-choose-a-tvs-diode-for-rs-232-rs-485-and-can-based-on-voltage-ratings.

    Regards,
    Max