TL081: Input Impedance

Mark Philip Felipe

Part Number: TL081

Hi Team, we have a customer that would like to ask the input capacitance value of TL081CP. He also wants to confirm if he could leave the offset pin floating.

We hope you could help us.

Thank you.

-Mark

over 4 years ago

0 Michael Steffes over 4 years ago

Guru 47435 points

Good luck Mark,

Nothing in the datasheet it seems, not sure what the model has, but if you have that up and running TINA or spice, here is an article on setting up to extract from simulation. Not sure you could trust the results unless the model was transistor level with good models.

https://www.planetanalog.com/input-impedance-extraction-and-application-for-high-speed-amplifiers-insight-9/

0 Ron Michallick over 4 years ago

TI__Guru*** 139906 points

Mark,

Based on other parts in same family as TL081, I'd expect about 6pF on each input (to ground) and 4pF between inputs. The offset pins can be left unconnected.

0 Mark Philip Felipe over 4 years ago in reply to Ron Michallick

TI__Genius 9705 points

Thank you Ron, I'll send this information to our customer.

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TL081: Input Impedance