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LP5912: Output Discharge, EN Connected to VIN

Ben Gardner
Prodigy 20 points
Part Number: LP5912

I'm considering using the LP5912 3.3V part for a new application.  I will need to connect "EN" directly to "IN" and am wondering if the Output Discharge FET will still be active when powered down. I don't have the eval board yet to measure this myself and if the output discharge is not active during power down, I may need to look at other parts.  

  • 0
    TI__Guru 55940 points
    Hi Ben,

    There must be some Vin in order to have enough headroom to drive the pulldown FET of the Output Discharge. As such, Vin tied to EN will not allow the pulldown function to engage while the LDO is fully functional (Vin > 1.6 V).

    If you do not have an external signal to drive EN separately, you could use a resistor divider so that as Vin drops, Ven will be less than 0.3 V. For a more robust solution, a voltage detector or voltage supervisor could be used in place of the resistor divider. This would allow the output discharge to be engaged for a time to help discharge the output rail while Vin still has enough headroom to power the internal circuitry.

    Very Respectfully,
    Ryan
  • 0 in reply to Ryan Eslinger
    Prodigy 20 points
    For my application, there may be voltage applied to OUT at anytime when this LDO is completely powered off. I may need to implement my own output discharge (blocking diode and/or output discharge through a P Channel FET and resistor). Thanks for your response...