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Original question:

TLV742P: External voltage application

TPS7A20: External Voltage Application

user6142633
Intellectual 440 points
Part Number: TPS7A20

Hi,

I would like to use TPS7A2018PDQNR.

Vin = 3.6V
Vout = 1.8V

And, Vout is connected with External Voltage at a specific timing.

Vext = 3.3V

According to datasheet of TPS7A20 series,Absolute maximam ratings of Vout is Vin + 0.3V

So, If Vin is larger than Vext, I think that I keep the rating and IC can operate without problems.

My understanding is correct ?

Please let me know if you have any concerns.

Thanks regards,

Hayakawa

  • 0
    TI__Genius 16816 points

    Hi Hayakawa, 

    Because of the internal active pulldown circuitry of this device, it will begin to sink current and it can potentially damage the device. 

    It is not recommended to connect this device like that. 

    Best,

    Juliette

  • 0 in reply to Juliette
    Intellectual 440 points

    Hi, Juliette

    Thank you for your response.

    I think that the internal active pulldown circuit does not operate if LDO is on.

    In that case, Is there potential to damage the LDO ?

    Thanks,

    Hayakawa

  • +1 in reply to user6142633
    TI__Mastermind 29320 points

    Hi Hayakawa,

    The active discharge is activated by pulling the EN pin low or if the input supply falls below the UVLO trip point.  In the block diagram, the EN pin connection is not shown and 'as is' it would be disabled.  In that case, Julie would be correct - this is not an intended mode of operation. If you can satisfy these conditions however, and EN is high and Vin is above the UVLO threshold, then the active discharge will not be engaged and this should be okay.  Keep in mind that when the 3.3V external supply is removed, the LDO will be unable to regulate the voltage until Cout is discharged down to 1.8V from an external leakage or resistance on Vout to RTN.  The LDO can only supply current, it cannot sink current (if the active discharge circuit is disengaged).

    Thanks,

    - Stephen