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TLV760: Is a diode from output to input needed for protection of TLV760?

Brad Levy
Prodigy 10 points
Part Number: TLV760
Other Parts Discussed in Thread: LM317

I know many three-terminal regulators are subject to problems/failure if the input supply is shut off and the output side is still powered (either from an alternate source, or by large output capacitors).

Usually the cure is a diode from the output back to the input, anode to the output, cathode to the input of the regulator.

Is this necessary with the TLV760 family  (5V or 3.3 variant)?  

In my case, the output cap is 1uF, and the load is a very-low-power processor.

I may want to apply external power to the processor (ie, to the TLV760 voltage regulator output) without input power to the TLV760 for in-circuit programming of the processor chip, although if need be I could have test fixturing provide input power to the TLV760 in this situation.

I have very little space on board, so if I can get by without the extra diode, I'd be a happy camper.




  • 0
    TI__Mastermind 37025 points

    Hi Brad,

    I will reply to your question within 1 business day.

    Thanks,

    - Stephen

  • 0
    TI__Mastermind 37025 points

    Hi Brad,

    I apologize for the wait on getting back to you.

    Yes, you will want reverse protection for this linear regulator if the output voltage could be higher than the input voltage.
    This device has an internal NPN transistor as the pass element, which unlike a PNP on the high side power path, does not offer inherent reverse voltage protection. One option is to choose a linear regulator with a PNP or P-channel high side pass element - both typologies have inherent reverse voltage protection.
    I find that a good reference for an NPN pass element is the LM317 datasheet.  There is a good application described, with a description of each component in the circuit in the datasheet.  I've copied that to this forum post to help.

    If I have answered your question, please click on the "Resolved" link.

    Thanks,

    - Stephen