I'm in the process of designing a little infra-red keyfob transmitter that is to be powered from a CR2032 coin cell. My concern is how best to deliver the high current pulses to the IR LED.
I have re-purposed another XmegaE5 board I have, to prototype the circuit and develop the software. This has a little piezo beeper on baord that quite expectedly loads the battery up far too much if activated, causing the voltage to drop and trigger BOD and even POR. None-the-less, if I don't use the piezo, I'd still like to run the IR LED at something like 20-40mA with range vs battery life the obvious trade off. (Incidentally, its using RC5 and I have reduced the pulse widths to about 25% for power saving.)
The prototype fortunately has a decent (22uF Al Electro) capacitor connected directly across the battery which supplies the high pulse currents. Is this likely to be the best way to do it? I'm most likely going to switch to a tantalum and an MLCC or 2 in the final design for lower leakage. Just wondering what other folks think about this. Is there a better cap chemistry to use? Maybe a supercap? Perhaps an alternative method?