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DS15BR400: Backpowering

Mitchell
Expert 4915 points
Part Number: DS15BR400

Hi Team,

My customer is thinking of using the DS15BR400TVS in a new design and had a question on backpowering. When the unit is off and there is a signal put into the input what happens? Is there any backpowering that occurs? We often see this behavior through ESD diodes from input pins to power rail, but we could not find information about the ESD scheme of the part in the datasheet. 

Thanks,
Mitchell

  • 0
    TI__Guru* 93670 points

    Hi Mitchell,

    When device does not have VDD and one of the lead is shorted to for example a supply. Then device tried to power up through the internal ESD diode. This diode has short circuit protection - in order of about 40mA - whereby it limits the current to prevent the device from burning up. Short circuit switch opens up once we go beyond 40mA.

    Regards ,, Nasser

  • 0 in reply to Nasser Mohammadi
    TI__Expert 4915 points

    Thanks Nasser. 

    They are planning on daisy chaining two of these modules on the same bus. They plan on having only one of the devices will be on at a time. On the datasheet, under the abs max ratings the CMOS input voltage max is VDD+0.3. Is it correct to interpret that theyshould not have a device that is off (VDD = 0) on the bus while it is active?

    -Mitchell

  • 0 in reply to Mitchell
    TI__Guru* 93670 points

    Hi Mitchell,

    Yes it is a good design practice(not having a device with VDD = 0 while it is active). This will provide a more solid design versus walking into unknowns.

    Regards ,, Nasser