TLC272: Allowable input voltage range in casse of VDD = 0V

Nobuhiko Wasa

Part Number: TLC272

Hi team,

In case of my customer's use case, it may happen that V+ = 2.5V when VDD is 0V.
Is there any concern for the case? What is the allowable maximum input voltage respect to GND when VDD = 0V?

Regards,
Nobuhiko Wasa

over 5 years ago

0 kai klaas69 over 5 years ago

Guru 140200 points

Hi Nobuhiko,

to prevent latch-up and to prevent the input circuitry from becoming destroyed the input current should be limited to under 5mA. So, insert a 1k current limiting resistor in series to the input pin of TLC272.

Kai

0 Nobuhiko Wasa over 5 years ago in reply to kai klaas69

TI__Intellectual 920 points

Thanks, Kai!!

0 Collin Wells over 5 years ago in reply to Nobuhiko Wasa

TI__Guru 62035 points

Thanks Kai!

Wasa,

If the condition where the voltage will be present while the op amp VCC is at 0V occurs regularly then we'll recommend that you keep the current into the pin much less than the +/-5mA abs max limit. Consider keeping the current below 500uA.

0 kai klaas69 over 5 years ago in reply to Collin Wells

Guru 140200 points

Hi Collin,

that's very useful information for me!! Thanks! I didn't know that...

Kai

0 Nobuhiko Wasa over 5 years ago in reply to kai klaas69

TI__Intellectual 920 points

Hi Collin,

Thanks.
My customer's case is 2.5V where 42V divided by 309K and 20K. So input bias current must be much less than 500uA.

Thanks,
Nobuhiko Wasa

0 Collin Wells over 5 years ago in reply to Nobuhiko Wasa

TI__Guru 62035 points

Hello Wasa,

The input current will only be 500uA when the op amp does not have power but the input is present. When the amplifier is powered the input bias current will be the typical datasheet specification levels.

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TLC272: Allowable input voltage range in casse of VDD = 0V