I am new on designing power management for circuits.
simulate this circuit – Schematic created using CircuitLab
I want to design a circuit to stabilize the 12v power input. I have a buffer amplifier at the signal input. I use OPA743, which is a rail-to-rail op-amp. I add a bypass capacitor (C3) at the power input and connect the input to both the power supply (pin5) and positive signal input (pin3) for the op-amp. I connect the negative signal input (pin4) to the output (pin1) and negative power supply (pin2) to GND.
I want to have a unity gain from this buffer amplifier. I want the circuit to buffer the 12v power input. I follow figure 4 of page 10 on the datasheet:
But I get an output voltage of around 4v, instead of 12v. Does anyone know what the problem is? Thank you!