I'm trying to build a voltage regulator that takes in a reference voltage and an unregulated voltage (to power the components, and this voltage is always greater than the reference voltage) and outputs the reference voltage over any capacitive, inductive or resistive loads.
Here's what I have so far:
The circuit has to be capable of outputting up to 5A at 6 volts and should have a relatively fast slew rate even at a high capacitive load (nearly 200 V/ms over 4uF load). It also has to have good load regulation (output voltage shouldn't drop over 200 mV at max load in reference to the reference voltage).
To satisfy these requirements, I've added a darlington pair since the 2N3445 is definitely capable of outputting that power, but requires a large base current, which the LM358 can't provide.
The issue I have right now is that when I attach a current source that emulates a 1 Amp load on and off at 1000 Hz, the overshoot and undershoot errors I'm getting are terrible. The output voltage jumps up to nearly 10V above the reference voltage for about 50us before crashing down to near 8V below the reference voltage before finally coming to rest at the reference. Is there anyway I can modify my circuit so this error is fixed?
I tried attaching a larger capacitance to the output (I have a 1 uF right now, this is the design capacitance, and not a load capacitance), but that didn't help out too much. Also attaching a larger capacitance over the smaller transistor's emitter (where the 2uF is hanging right now) destroys the slew rate (I crash down to nearly 8 V/ms when I hang a 22 uF there.)