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SN65HVD1040: about abs-max spec

Guru 11170 points
Part Number: SN65HVD1040
Other Parts Discussed in Thread: TCAN1044A-Q1

Hello E2E,

The datasheet said the device has voltage tolerant min -27V to max 40V on CANH and CANL.
Our customer tried test connect 16V DC bias voltage on the communication line (CANH and CANL), that device damaged.

1. Does the spec have a limit for the voltage superimposed time?
2. Is the purpose of the spec to allow transient voltages on the communication line, and is it not supposed to be short-circuited with other circuits?

Best regards,

  • ACGUY,

    Absolute maximum specifications represent indefinite connection unless otherwise mentioned.

    CAN transceivers are specified this way to be able to withstand situations where the CAN lines are inadvertently connected to supply voltage during a fault condition. These absolute maximum conditions are tested to ensure they are met.

    What is the mechanism of damage you're seeing? There is a possibility of high overshoot during some of these tests.

    Was the device attempting communication (i.e. driving) when you observed this?



  • Hi Danny,

    Thank you for your reply.
    They connected bias 16-V voltage on CAN bus the transceiver during communication.
    The device sinked high-current (over 1A) from biase source, the device damaged.
    Therefor, I thought that this device has limit for biasing time to CAN bus.

    Is it normaly?

    Best regards,

  • ACGUY,

    Yes, there is current limiting on CAN transceivers as a protection feature during fault conditions. For the SN65HVD1040, this is given as IOS(ss) Short-circuit steady-state output current. However, this doesn't address thermal considerations.

    During a fault condition, when shorting CANL to GND (for example), the device could sink near 100 mA. This corresponds to approximately 1600 mW of power dissipation, which could thermally damage the device. Thermal damage could then lead to the formation of a low-impedance path to GND, which would explain the high current consumption.

    Have you done this test at lower battery voltage levels, or with different environmental thermal characteristics, to see whether the same behavior is observed?

    Also, as a separate question, have you considered our newer portfolio of CAN transceivers such as the TCAN1044A-Q1?