LM2903-Q1: State of LM2903 output when unpowered

Greg Amidon

Part Number: LM2903-Q1
Other Parts Discussed in Thread: LM2903

Team,

I'm assuming that the LM2903's output is high impedance when unpowered, but don't have one here in the lab to double check. Can you please confirm?

Thanks!

Greg

over 2 years ago

+1 Clemens Ladisch over 2 years ago

Guru 243980 points

Yes. When V_CC is at 0 V, then no current can flow into the base of the output transistor, and it is off.

0 Greg Amidon over 2 years ago in reply to Clemens Ladisch

TI__Expert 5240 points

Thanks for the confirmation Clemens!

+1 Paul Grohe over 2 years ago

TI__Mastermind 49966 points

Hello Greg,

Yes. As Clemens said, the output device is a transistor with no base drive - but there may be some tiny nano-amp level leakages to GND and/or Vcc. The pins do not have upper ESD clamps to Vcc, so the inputs and output can be taken up to 36V without damage, even when Vcc=0V. With the common pull-up resistor values...you probably won't even notice a difference between powered and un-powered.

Vcc=0V is not a valid operating condition, so leakages are not not characterized..

0 Greg Amidon over 2 years ago in reply to Paul Grohe

TI__Expert 5240 points

Thanks Paul, I appreciate the confirmation that there is not a leakage path from the output that may bias on the transistor. That was my concern!

Regards,

Greg

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LM2903-Q1: State of LM2903 output when unpowered