LM2901 output capacitor

Tomohiro Nagasawa

Expert 1710 points

Other Parts Discussed in Thread: LM2901

Dear support team

My customer want to design circuit using ceramic capacitor of 4.7uF as output capacitor of LM2901 and discharging it.

And I have two question.

Q1) Does it have any problem using 4.7uF as output capacitor?

Q2) If it does not have any problem,Is it possible that removing discharge resistor?

Thanks

Best Regards

Tomohiro Nagasawa

over 8 years ago

0 Ron Michallick over 8 years ago

TI__Guru*** 140136 points

Tomohiro-san,

What is the maximum voltage on the capacitor? I need it to calculate power dissipated.

0 Tomohiro Nagasawa over 8 years ago in reply to Ron Michallick

Expert 1710 points

Hello Ron-san

Thank you for quick response.Max voltage is 5V.

I hear that 29 series of competitier have no problem, but how about LM2901 of TI?

Thanks

Best Regards

Tomohiro Nagasawa

0 Ron Michallick over 8 years ago in reply to Tomohiro Nagasawa

TI__Guru*** 140136 points

Tomohiro-san,

The output will simply discharge the capacitor at the current capability of the output transistor (base current * beta) which is about 20mA.
estimated discharge time is CV/I = 1.2mS. The time in max current operation is low. The energy in capacitor is 1/2CV^2 = 60uJ, also very low.
Lastly, 5V is well below the maximum voltage therefore bipolar secondary breakdown is impossible.

I see no problem with the capacitor being directly on the output pin.

0 Tomohiro Nagasawa over 8 years ago in reply to Ron Michallick

Expert 1710 points

Michallick-san

Thank you for very quick response.

I'm going to answer it to customer.

Regards

Tomohiro Nagasawa

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LM2901 output capacitor