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TLV755P: TLV75528PDQNR

user728150
Prodigy 30 points
Part Number: TLV755P

Hi, In my design I used a TI LDO regulator TLV755P series (TI PN: TLV75528PDQNR). 

I need your feedback about the LDO output capacity & restriction.  Is there a problem if we apply a voltage to the regulator output without applying voltage to the regulator input?

The reason for this request is that the programmer of the microcontroller can apply a voltage on the output pin of the regulator. See the diagram below.

Conditions:

     - No power at VDC-IN

     - 3.3 volts from the programmer unit apply to the LDO output pin

(resume, 0 volt LDO iinput pin and 3.3 volts apply to the output LDO pin.)

 

  • 0
    TI__Guru 55940 points
    Hi ,

    While TLV755P does not have any reverse current protection internal, your schematic shows that you have provided reverse current protection with D1. A Schottky diode from OUT to IN provides a robust path for the reverse current protecting the LDO. Schottky diodes are used for this purpose due to their low forward voltage.

    Very Respectfully,
    Ryan
  • 0 in reply to Ryan Eslinger
    Prodigy 30 points
    Thanks for your quick answer Ryan, but in my case it is important to know in this case we will have only one supply in the same time. In case where we will use the 3.3v (supply by the debuger) the VDC_In input will be unconnect (this entry will not be connected). In this case the Schottky diode will not be polarized
  • 0 in reply to user728150
    Prodigy 10 points

    I'm working with user728150,

    What we are trying to know is if we will damage the TLV755P Chip if we apply 3.3 Volt to the 2.8V output.

    Thanks for your help.

  • 0 in reply to Raphael Nadeau
    TI__Guru 55940 points

    Hi ,

    As long as you leave the Schottky diode in place to protect against the reverse current (which will charge your input capacitors when VDC_IN is left floating), you are able to apply a bias voltage to the output higher than Vin (which is floating in your case).

    Vout should not be biased above 5 V so that you remain within the Recommended Operating Conditions.  A 3.3 V bias is not an issue so long as the Schottky diode remains to protect against reverse current.

    Very Respectfully,

    Ryan