LM2902 parameters

Veerasamy Vasudevan

Other Parts Discussed in Thread: LM2902, LM324

Hi,

I am performing Stability analysis for LM2902 based circuit. From datasheet, I get that the Open Loop Gain is 100dB and unity gain BW is 1MHz.

However I do not get following details.

1. Phase margin at 1MHz

2. Output Impedance

3. Input pin capacitance

Please share these details if available.

Regards,

Veerasamy

over 10 years ago

0 Ron Michallick over 10 years ago

TI__Guru**** 174596 points

Veerasamy,

1) 35 degrees with only 30 pF load (better with DC load)
2) 30 ohms (PNP sinking or sourcing)
3) A couple pF (certainly less than 6pF)

0 Veerasamy Vasudevan over 10 years ago in reply to Ron Michallick

Intellectual 390 points

Hi,

The Phase Margin of 35 degree seems to be less. 30pF is very nominal load. Are you sure about the value. With 35 degree phase margin, the unity Gain buffer with this OPAMP will be unstable.

Can I get SPICE model for this OPAMP?

Regards,
Veerasamy

0 Ron Michallick over 10 years ago in reply to Veerasamy Vasudevan

TI__Guru**** 174596 points

Veerasamy.

35 degrees is certainly not ideal. Add gain and PM gets much better. Add resistive output load (to either rail) and PM improves.
External compensation can be used for any capacitance and unity gain.

LM324 model that is also LM2902 model.
www.ti.com/.../sloj043

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LM2902 parameters