Originally Posted by Sean H
Paul- Specifically, what is it about the AD823's technical parameters that might make it an ideal chip to use in the 2.5 power supply and how is it better than the OPA's you mentioned? I'm not technically inclined enough with this stuff to know. I have an AD823 on hand that I could put in the opamp position in the power supply. I have an OPA2107 in there now. Just curious, sounds intriguing. Thanks!
Serious apologies for the delay in responding. I've been on the jury of a rather nasty criminal case and I've spent the last few weeks in a state of high dudgeon. Its over and the SOB isn't going to be out of prison for the next 30yrs.
I'm actually quite embarassed by my recommendation of the AD823 as my intent was to suggest the AD826. The opamps in that position provide a correction signal from a comparison of the output voltage against a voltage reference/divider network. As this reference node is typically low impedance, a bipolar input chip would normally be chosen, for lowest noise. The AD817 bipolar single amp chip is typically used in Suzler and Jung regulators and the AD826 is close to a dual version of it. Then again, I don't have a 2.5, but rather a 2.0 which lacks opamp controlled voltage regulators. But if the voltage ref and output is fed to the regulators opamp from high impedance nodes, the AD823 is an excellent choice. The 823 would work very well in that environment, which is typical in a output servo circuit in power amps.
As you've been experimenting with the National LM4562, and if you want to experiment with bipolar opamp for voltage regulation, the National chip might give very pleasing results, dunno..... If I had a Zhaolu 2.5 I'd trace the circuit and base my suggestions on more accurate info.
Again, sorry for the delay and the 'misinformation' and can only console myself with 'alls well that ends well'.