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LMV321A: Partial-Power-Down Mode

yana
Prodigy 240 points
Part Number: LMV321A
Other Parts Discussed in Thread: LMV321, LM10

Hello,

I have a question about "LMV321" or "LMV321A"

In my circuit, 5.0V (1Kohm pull up) is applied to "OUT" pin, while VCC is "Low".

Can I use "LMV321" or "LMV321A" in this situation?

If it is not possible, could you please introduce other operation amplifiers?

Best regards,

  • 0
    TI__Guru*** 139936 points

    Hello Yanagawa-san,

    Is the goal for the output to stay high when op amp is unpowered?

    Is the op amp connected as a comparator? If yes, try swapping the inputs and adding a NPN or NMOS transistor to the op amp output to make the final output open collector/drain.

    How high does the OUT pin need to be? Would 4.9V or 4.8V be good enough? Adding a diode to the V+ pin of the op amp lets the OUT pin power the op amp using pull up resistor current.

    Op amps that allow OUT > Vs+ are extremely rare. The only one I know is LM10 and I learned that accidently yesterday.

    Can you provide a partial schematic or a drawing of the circuit in question?

  • 0 in reply to Ron Michallick
    Prodigy 240 points

    Hello,

    Thank you for your reply.

    I will consider other solutions.

    I attach the partial schematic for your reference.

    Regards,

  • 0 in reply to yana
    TI__Guru*** 139936 points

    The schematic is helpful.

    I still need to know the answer to still critical question: "Is the goal for the output to stay high when op amp is unpowered?"

    If the answer is no, then the circuit will work as drawn. The LMV321A will pass current from its output pin to its V+ (power supply) pin. This is not harmful to LMV321A by itself . Having the output pin connected directly to an external connector does present a ESD/EOS risk to the LMV321A.

  • 0 in reply to Ron Michallick
    Prodigy 240 points

    Hello,

     Thank you for your support.

    Regards,