Hi Orlando,

"My circuit reads the output, do the calculations and show the maximum, minimum, average voltages "

Right now I think you can continue with the setup. For the purpose what you described this may be adequate.

"I looked the IC that you said, but I think it's not what I need... "

You are right. You don't need an IC meant for watt meter applications, as you only want to monitor the acV level.

"I read something about one OP-AMP from analog devices that could withstand up to 500VAC in its inputs, but I don't remember if it was a peak value or if it is a operational value."

Forget if its peak or rms. Would be far more safer to handle a scaled down sample ( transformer, resistor divider etc ) of the ac mains.

Raghu