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DP83TC813R-Q1: 100BASE-T1 and CAN tolerance

Tom Rice
Prodigy 20 points

Part Number: DP83TC813R-Q1

Hello,

We are designing a new product that has two configurations: one for 100BASE-T1 communication and another for CANbus communication. These will both utilize same physical pair of pins on a connector, which leaves the possibility of a 100BASE-T1 system to get connected to a CANbus system on accident.

We'd like to know if the DP83TC813R-Q1 is tolerant of connecting to a CAN bus without damage. We see that it has abs. max ratings of –0.3 - 4V on the MDI pins, and we would expect a CAN bus (specifically CAN 2.0 / FD-CAN) with proper termination to not violate those values, but we would like your thoughts.

Edit: In addition, we see the DP83TC815-Q1 has the following line: "48V ready: VBAT transients to MDI up to +/– 70V" in the datasheet, but the same abs. max ratings of –0.3 - 4V on the MDI pins. Can you please clarify the transient voltage ratings of the DP83TC813R-Q1?

Thanks,
Tom

  • +1
    TI__Mastermind 28602 points

    Hi Tom,

    I agree, I do not expect CAN bus to cause absolute maximum spec violation of the Ethernet PHY, or cause any damage. This will be similar to connecting another single pair ethernet PHY. DC blocking caps in the Ethernet path will block any DC voltage from the link partner, AC swing of CAN bus will not exceed 4V. 

    DP83TC813 and DP83TC815 both I expect no damage from connecting to CAN bus. DP83TC815 is more robust to transients. Where DP83TC815 is protected from VBAT transients +/-70V, DP83TC813 is roughly +/-12-16V without external diode, or external diode can be used to protect again higher transients. 

    Thanks,

    David

  • 0 in reply to David Creger
    Prodigy 20 points

    Hi David,

    Thank you for the clarification! 

    David Creger said:
    DP83TC813 is roughly +/-12-16V without external diode

    Can we request this value be added in the datasheet somewhere? I looked through again, there is no information of transient tolerance on MDI pins, only HBM ESD and absolute DC ratings. 

    Thanks again,
    Tom

  • 0 in reply to Tom Rice
    TI__Mastermind 28602 points

    Hi Tom,

    This is not something currently defined for DP83TC813, but I will share the request with my team.

    Thanks,

    David