I want to power an 88pa from a supercap. What I would like is to have a way to "hold" the AVR from starting until the VCC reaches something "comfortably" over 1.8V (like, 2).
The problem is that the cap takes a long time to charge (Induction charging, takes "forever"), so I don't want the AVR to try to boot, dip the VCC by doing so under the necessary voltage (or ripples in the rail), halt again because of that, start again etc etc and thus is fact make matters worse on the charging cap.
What I'd like is to be able to have the AVR start "cleanly" and use the first cycles to put itself into sleep mode and monitor the rail from there, in low power.
So I've been wondering how to either, use a transistor to hold the whole AVR rail offline until the VCC reaches 2V, possibly with a voltage divider on a transistor... of course I don't like the voltage divider, since it itself sucks uAs...
Alternatively, I could try to hold the AVR in reset until that condition is reached, but I've been wondering how to do that cleanly, and cheaply in terms of power.
Any suggestion ?