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TLV7041: Supply isolation

Yen Nee Lee
Prodigy 120 points
Part Number: TLV7041

Hi,

From the datasheet, Vin spec is VCC + 0.1V, and in my design there is possibility of Vin supply available first before VCC,.

1) Is disconnecting the ground before VCC available able to protect the op amp? Something like below. Without the ground reference, will Vin damage the part?

2) With the above configuration, without VCC and ground, with Vin (at pin 3)=5V, will i see any voltage at output pin 1?

Thanks!

  • 0
    TI__Mastermind 24480 points

    Yen

    thanks for your post. The good news is that this family of comparators allows a voltage up to 6.5v on the input without being damaged regardless of the presence of VCC. We call this fail safe inputs. The VCM you are referring to is for normal operation range where specs on the EC table are warranted. It sounds like your main concern is damaging the device and output state under the condition of no VCC. In regards to the output, the output will be high Z until VCC reaches operational voltage range.

    Chuck

  • 0 in reply to Chuck Sins
    Prodigy 120 points

    Hi Chuck,

    Thanks for the great news. Is there a limit to how long the Vin (+ or -) can be exposed to a voltage <6.5V without the VCC supply?

    Thanks.

  • 0 in reply to Yen Nee Lee
    TI__Mastermind 24480 points

    That’s a good follow up question. There is no time limit. Glad this will help your application. Seems like you have a unique use case. I may follow up offline to learn more if you don’t mind. 
    Chuck