I'm trying to pick an op-amp and I'm having trouble figuring out if the op-amp needs a positive and a negative power supply or if I can connect it to ground and the positive supply.
What do I need to look for in the datasheet?
Also, where do I find the "drop-out" of the output compared to the rail voltage?
Best Answer
Most if not all op-amps can be used in either configuration. Voltage is relative, and "ground" is just an arbitrary potential that you assign the value of 0 volts. There are op-amps "optimized" for one configuration or the other, but they can be used in either. This op-amp, for instance, is "optimized for single supply operation", and they emphasize features like:
but "Specifications at ±15V are also provided."
Op-amps meant for single-supply often have rail-to-rail outputs, which will usually be featured on the front page of the datasheet. To find the "drop-out", look for a graph like "Maximum Output Voltage Swing vs Load Resistance" in this datasheet.
A Single Supply Op Amp Circuit Collection