I am working on an ultra low power infrared wake-up circuit for a microcontroller (Atmel XMEGA). I have IRDA comms working but the receiver uses too much current to keep on all the time. I need to run for five years on a single battery, so <3uA is the goal. Cost is always a factor, as usual.
In fact my company already produces other products with such a wake-up circuit but they use somewhat expensive op-amps and take up quite a bit of board space. I'm thinking it can be done with just a single comparator, something like an MCP6546.
(can't post images, look here)
The resistors will set the comparison voltage based on what photodiode we pick, obviously. The reason for using it in photovoltaic mode like this is to reduce power consumption.
Will this work? Can it be improved upon? I found this design which is similar but uses a comparator with built in reference voltage.
I could do that too, but it would need to be something like an MCP65R41 that costs a lot less and is available.