This application note states that zero crossing detection can be achieved in an AVR with just a couple of resistors. However, it forgoes galvanic isolation and this is not acceptable for me.
I would like to supply CMOS control signal to a triac, in the same time monitoring mains voltage for zero crossing. Is there an opto device, capable of both these tasks at the same time. Preferably a small, DIP, not exceeding $1 device?
This is an AC input optocoupler:
And this is an optotriac, used for controlling power triacs:
Having them both in a sigle package, pointing in opposite direction, would, IMO, simplify and make cheaper implementation of simple AC load control.
Best Answer
Yes, there are plenty of optoisolators that can do what you want. Look around at the usual suspects, like Mouser, DigiKey, or whatever your favorite supplier is. There should be plenty to chose from, especially if you can live with a few µs delay.