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MAX660: Output failure mode

Danilo A.
Mastermind 26940 points
Part Number: MAX660

Hi Team,

Can you please help with this inquiry of our customer?

My associate is claiming this part has a fault condition whereby the inverted output can go positive during start up mode 

I.E. as a +3 to -3V converter that during start up the output goes positive and tracks the +3V input. He suggests we add a protection diode to Vout to block this .. I am having difficulty understand how this could be possible, any thoughts?

"add Schottky (ZLLS410TA) diode from -3V to GND to prevent -3V bus form going positive in startup and fault conditions."

Regards,

Danilo

  • 0
    TI__Mastermind 23400 points

    Hi Danilo,

    Thanks for using the e2e forum.
    I am sorry you did not receive a response until now.

    I will look into this behavior and give you an update by tomorrow.
    In the meantime, can you share a schematic of the customers application?
    This should make it easier to pin down the source of the error.

    Thank you and best regards,
    Niklas

  • 0 in reply to Niklas Schwarz
    TI__Mastermind 23400 points

    Hi Danilo,

    One additional request,
    Could you provide a measurement of the failure from the customer?

    Thanks you very much.
    Best regards,
    Niklas

  • 0 in reply to Niklas Schwarz
    TI__Mastermind 26940 points

    Hi Niklas,

    According to our customer,

    There is no failure we are using the part exactly as called out in the data sheet I posed a question specifically

    We were told by co worker that unless we added a schottky diode between output pin 5 and ground the max660 locks up during start up.

    Is this True? Yes or no and why

    Regards,

    Danilo

  • 0 in reply to Danilo A.
    TI__Guru 61535 points

    Hello Danilo,

    Ah, so this is not an issue, but you fear that it could happen, now I understand. I did not see this behavior up to now, so I would expect that this is not an issue, but if you want to be on the safe side, you could place a diode on the output and not populate it.

    Best regards,
    Brigitte