LM7332: Low Rout GPAMP

Charles Zhang1

Part Number: LM7332
Other Parts Discussed in Thread: TLV9102

Hi Team,

My customer is finding suitable OPAMP to implement a low Rout buffer circuit for ADC input, I have found that LM7332 might be technically feasible, however, LM7332 is an old part, so I am wondering if we have some newer parts could meet the specs below-

1. Dual Channel

2. Close Loop Output Resistance <= 50 Ohm

3. BW >= 0.7MHz

4. VCC > 12V

Pls help to recommend the alternatives, thanks.

Regards,

Charles

11 months ago

0 Ron Michallick 11 months ago

TI__Guru**** 152946 points

Hello Charles,

TLV9102 is one of many choices. I picked this one for rail to rail input.

https://www.ti.com/amplifier-circuit/op-amps/products.html#78=Out&480=2&1261max=12%3B180&23typ=1%3B8000&451typ=0.02%3B10&sort=1130;asc&

0 Charles Zhang1 11 months ago in reply to Ron Michallick

TI__Expert 3110 points

Hi Ron,

My customer is concerning about the output resistance of OPA, the effective Zo should be less than 50 Ohm.

I have checked TLV9102 datasheet, it only shows 600 Ohm open loop Zo, do you have a close loop Zo spec of TLV9102?

Or do you have lower Zo option?

Regards,

Charles

0 Ron Michallick 11 months ago in reply to Charles Zhang1

TI__Guru**** 152946 points

Charles,

The [closed loop output impedance] = [open loop impedance] / [1+loopgain]. Loop gain = [op amp open loop gain] * [feedback gain] (feedback gain is usually less than 1)

Why do they say 50 ohms?

0 Charles Zhang1 11 months ago in reply to Ron Michallick

TI__Expert 3110 points

Hi Ron,

It is based on ADC input's recommended range, it needs a buffer with <50 ohms Rout.

Regards,

Charles

0 Ron Michallick 11 months ago in reply to Charles Zhang1

TI__Guru**** 152946 points

Charles,

How fast/often does the op amp output change? Please show the schematic for this op amp stage. I'll simulate close loop ROUT.

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LM7332: Low Rout GPAMP