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TLV1117LV: Will chip be damaged when connecting 3.3V to output but leave input floating?

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Part Number: TLV1117LV

Hi team,

My customer is using TLV1117LV to convert 5V to 3.3V. But there is a special use case in customer's design that the TLV1117LV input is not powered on but the output is connected to a 3.3V voltage. I want to check with you if TLV1117LV will be damaged under this situation?

I think the 3.3V on the output will pass to the input side through the diode of the internal MOS to generate a ~3V voltage at the input pin. Will the chip be powered on due to the ~3V input? Is there any risk here? Thanks.

Best regards,

Wayne

  • HI Wayne,

    The only concern here is how much current can flow? As you correctly state, the internal diode will cause VIN to charge up. Charging up whatever capacitance is on VIN may result in high currents which can damage the device. A common guideline given for maximum reverse current is to make sure it is less than 1/10th of the rated load current.

    A good recommendation to mitigate this risk is to add a diode in parallel with the LDO to provide a path outside the LDO to charge up VIN.

    I hope this answers your question.

    John Cummings 蔣康明
    Texas Instruments 德洲儀器
    Johncummings@ti.com

    Please click the "Resolved" link at the bottom of this post if I have answered your question.

    Thank you,

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