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LM2901: Input capacitance

Andriy Tkachuk

Prodigy 180 points

Part Number: LM2901

Hi team,

My concern is about a decrease in the slew rate of an applied square signal to the input of the LM2901 through 51k resistor, as shown in the picture.
Could you please suggest if this is due to the large input capacitance and what is the input capacitance of LM2901?

Kind regards,
Andriy.

over 3 years ago

0 Paul Grohe over 3 years ago

TI__Mastermind 49896 points

Hello Andriy,

151pF is wayyy too high for the LM2901 input. It will be more like 2-3pF looking into the input pin.

What else is connected after the resistor? The amount of capacitance added by long PCB traces, particularly with thin layers, can be surprising.

0 Chuck Sins over 3 years ago in reply to Paul Grohe

TI__Mastermind 23395 points

Please let us know if you need any additional assistance, otherwise we will close the thread at the end of the week.

thanks

Chuck

0 Andriy Tkachuk over 3 years ago in reply to Paul Grohe

Prodigy 180 points

Hi Paul,

Thank you for your reply.

The LM2901, which was mistakenly placed in our application, was from ON Semiconductor. Replacing it by LM2901 from TI fixed the problem.

Thank you again and sorry for any inconvenience.

Kind regards,
Andriy.