I've designed a little PCB that basically combines a boost converter, single cell LiPo charger, and an attiny85, designed to run off a 400mAh LiPo cell.
I've just removed the polyfuse and stuck my DMM in it's place, and put it on the mA setting (and probes in the mA socket etc), and it's power draw in shutdown (boost converter disabled) is fluctuating between about 1.5mA and 2.5mA, which is much, much more than it should be.
The boost converter's quiescent current draw is specified as 20uA max. The battery charger specifies around 10uA max. The only other thing connected to the battery directly is a resistive divider that totals around 2.2Mohms. Yet I'm getting on the order of 2mA?
I'm wondering whether this is just the DMM messing with me, or whether something is actually wrong with the circuit?
https://dl.dropboxusercontent.com/u/203420/Collar/Sheet1.pdf(Note that I've manually added a 1.8Mohm resistor on pin 7 of the attiny where it connects to the battery, as I was getting current backfeeding through the ESD diodes, and even completely disconnected it for the test).
Edit: Just logged it with the DMM, started by discharging the caps and ran it for 240 seconds. Y axis is uA and X axis is seconds .. really strange. No idea what's going on here
Help?