Both of these chips provide a constant supply 5V. My guess is, based on price and datasheets, the ref02 is much more precise and does better under varying temperature characteristics. Watching Peter Oakes video tutorials on modular power system, he uses three different options for adjusting the op-amp input voltage; zener diode, JFET with zener diode, and a ref02 module. He chooses the JFET with zener to give pretty precise control, but says for the best precision to use a ref02 module. I was wondering why a LM7805 (maybe $.50) wouldn't function in the same way? The output stage in the schematic will probably be mosfets or darlingtons or something, this is just representative and my question is related to the input.
All credit on the schematic and circuit design goes to Peter Oakes (thebreadboardca).
simulate this circuit – Schematic created using CircuitLab
Best Answer
Functionality is the same (apart from the trim feature on the REF02) but not performance....
The REF02 has an output voltage specified at 5V ± 0.2%
The 7805 is specified by Fairchild as 5V ± 4%
The output voltage temperature stability of the REF02 is 10ppm / degC. This is equivalent to 50 uV / degC.
The 7805 equivalent spec is 5 mV / degC
The long-term stability of the REF02 is ± 100 ppm (0.5 mV) over the first 1000 hours and gets better for the 2nd 1000 hours. I've not seen this specified for a 78XX regulator so it's not really guaranteed.
Horses for courses.