I have a question regarding optimising design for ultra low power consumption device. I'm trying to develop a remote sensor node that should measure and send data every few hours.
Currently I have an RTC (DS1337) that wakes up my MCU (ATMEGA328P) from deep sleep via hardware interrupt. While the sleep current is fairly low ( avg 76 uA), it is still a fairly large amount if I aim for a device to run in the wild for couple of years.
Could I instead, use the RTC to ENABLE/DISABLE the 3.3v LDO (MIC5404) thus shutting completely down the MCU and have the RTC runs on a separate coin cell battery? I think this is called power-gating. What will be the hidden disadvantage ?