Can the ADA4870 drive cap loads greater than 1uF?
Yes the ADA4870 can driver capacitive loads greater than 1uF, however a larger capacitive load reduces the amplifiers bandwidth and slew rate.
I hope this helps.
To follow up on this - looking at applications to drive >10uF. I only need x1 gain.
What's the minimum Rs for stability/<3dB peaking with large cap loads? Datasheet suggests 0.3Ohm, but is this also true for x1 gain? And a related question - if I use, say 0R5 - is there any advantage, again in terms of stability, in increasing the gain for a given capacitive load?
This is a decent app note on op amp stability:
Thank you for the app note suggestion - I've added it to my collection although its focussed on voltage feedback opamps - not sure if CFA are different in that respect.
My question was specifically regarding the ADA4870 though - and what the minimum Rs is for Cap loads >10uF at unity gain (the datasheet doesn't show the graphs for a x1 gain).
Never really thought about that, but I think it's the same. The output is a voltage output.
I'll ask some colleagues tomorrow. You could try spice or breadboard....
See fig 69 and fig 70.
Thanks, but Figs 69 and 70 are for x2 gain, I was wondering about x1 gain.
Especially versus temperature - fig 25. shows significant peaking at 100degC, which is not present at 25degC
The best thing to do is to try it out on the bench. You can also:
Connect a 470 ohm resistor from your source to the non-inverting input of the op amp.
Connect a 470 ohm resistor from your source to the inverting input of the op amp.
Connect a 470 ohm resistor from the op amp output to the inverting input.
That will give you a signal gain of +1 and a noise gain of +2.
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