I’m trying to design a tiny-as-possible voltage regulator that is kinda-efficient as it will run on ~1200 - 2200 mAh LiPo batteries.
The problem is that the input voltage is not fixed, it might run on 2 or 3 cell LiPo or Lion, or NiMH between 7.2 - 9.6 volt.
To provide a stable 5v input, I’m thinking on using an L7805 as a regulator, but to save battery life, I also plan to use capacitors and a P-FET to switch on/off the regulators.
The controlling would run on an Attiny84 that would monitor the input voltage and if it falls under the limit, it switches on the P-Fet that would let the L7805 to charge the capacitors, and if the voltage raised above a limit, the P-Fet is turned off.
Note: The P-FET’s number is not the actual I’m planning to use, it would be a logic level FET.
Beside the control circuit that the battery will also supply a high-load DC Motor (~20-25 amper) which will be controlled with an N-FET.
To monitor the battery voltage, I also added a really high Ohm voltage divider. The load between them would be basically zero, as all I need them to do is monitor the voltage.
Would this “theory” work in practice?