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TCAN4550: The schmatic diagram review for TCAN4550RGYR

Zhang Liang
Genius 5415 points

Part Number: TCAN4550

Hi,

Our end customer feedback us TCAN4550RGYR has the return issue, and the failure rate is about 4%.

Issue Description:

1. The error rate of the client will significantly increase within one week of use, 
    and the system will not be able to recognize the chip the next week;
2. Measurement reveals that the impedance of pins 10 and 11 of the defective chip is low.
 
The schematic diagram:
TCAN4550RGYR SEAVO schematic diagram.png
 
The PIN10 and PIN11 ground impedance:
PIN Normal  Failure 1 Failure 2 Failure 3 Failure 4
10 1650 0 0 1659 0
11 858 859 796 0 0

Please kindly review our schematic diagram and check if there are any ESD design issue, if not, plesae advise if we need to submit the FAR to CQE for the return process, thanks. 

  • 0
    TI__Mastermind 37531 points

    Hi Zhang,

    I see that there are two different GND's in the circuit, one for the device and the other for the CAN termination.  This is not common and may be causing the damage to the CANH and CANL pins if there is an offset voltage between the two GND potentials.  The current flowing through the CANH and CANL pins will use the device GND which is different than the GND used for the components on the CAN pins. 

    The inductance of the common mode choke can also amplify the voltage levels on the CAN pins due to sudden changes in current coming from transient or short-circuit faults that could lead to over-voltage stress on the pins resulting in damage.  Different GNDs make increase the risk of such an event.

    I would suggest the same GND be used for everything, or tie the two GND's together on the board to prevent a voltage offset forming between them.

    I didn't see anything else in the circuit that I think would cause damage to the CANH and CANL pins.

    Regards,

    Jonathan