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DS16F95QML reverse power

Hans
Genius 12725 points
Other Parts Discussed in Thread: DS16F95QML

Hello Team,

Can you please confirm that the DS16F95QML (EIA-485/EIA-422A Differential Bus Transceiver) is NOT protected against reverse powering.
We use this device for a CANBus application. Our measurements show, that if pin A and B is connected to 2.5V, the VCC pin goes also to 2.5V if the device is unpowered.

Thanks and Best Regards,

Hans

  • 0
    TI__Genius 17035 points
    Hi Hans,

    If by reverse powering, you mean having a voltage on pin A while Vcc is at ground, the part is protected against this.

    The absolute max voltages listed in the datasheet for the bus pins (A and B) are independent of the supply voltages. The current flow between pin A and Vcc is minimal and will not damage the part.

    Reversing Vcc and ground will eventually damage the part.
  • 0 in reply to Kirby Kruckmeyer96848
    TI__Expert 3820 points

    Hello,

    Here some comments from the customer:

    "The Vcc is in our case floating, GND is on GND, A and B on 2.5V.

    We have also other parts connected to Vcc that could be reverse powered...

    But we can use clamping diodes on Pin A and B, right?"

    Thanks and regards

    Adrian

  • 0 in reply to Adrian Helwig
    TI__Genius 17035 points

    It depends upon the status of the other pins.

    If all pins but INA, INB and GND are floating, then this should not be a problem.

    If any of the enable pins, RO, REb, DE and DI are not floating, but connected to some potential, then putting a positive voltage on GND could damage the part.