I am using MCP4728 DAC which I am controlling nicely from the microcontroller. On its output I have connected the op-amp in buffer configuration(non-inverting input is the signal from DAC, inverting input and output are connected together), all powered with 5V on positive rail and gnd on negative rail. Op-amp part is AZV321(rail-to-rail).
Output of buffer op-amp goes through two more stages of amplification which end up in the base of darlington transistor. So, a little current is needed from the buffer.
What happens in my case is that when I connect the circuit, only the connected DAC channel stops working - it doesn't give any voltage out anymore.
I find it hard to understand what happens. From my understanding, op-amp is correctly connected and there shouldn't be any problems. I have tried switching DAC & op-amp, in case I have soldered then wrong.