Hey,
I hope someone can point out what I'm missing... I've been playing around with TLE2022 op-amps, my main goal being to get a reliable DC voltage follower that goes all the way to 0, on single supply.
Now I have a 5.1V Zener diode plugged into the amp's output, and from there on I have direct negative feedback to the inverting input. My positive power rail is 18V, negative power rail is 0. That's all of the setup.
First I plugged the non-inverting input into the 0V power rail. On the output I got ~0.7V, which dropped across the Zener, and I got actual 0 Volts at the end. Then, I started playing around with various voltage dividers... I gave it 90 millivolts, and it followed quite perfectly. Then 1.8 Volts, no problem at all. Then 9 Volts, and... I got a whopping error of ~0.6V!
First, it's weird how it worked at low voltages, but at 50% of the rail I'm getting such an unacceptably high error... Also it somehow makes me wonder that the error is about one diode drop... Any idea?
Next up is, I'll try to just divide the input voltage down, and set a gain higher than one to multiply it back up... Maybe it will remove the error.
Is it possible that I'm already getting clipping? The Zener drop is 5.1V, the voltage to follow 9V... That's 14.1V, well below the positive rail...