I am still new to electronics and I am looking for a low noise and efficient way to provide 5V and 3.3V from AA batteries. My circuit requires 3.3V/200mA 10% of the time and less than 1mA the other 90%. 5V is 99% <1mA, 1% 50mA.
Here is how I am currently approching this problem :
I could use 4xAA and step-down converters but given my circuit requirements the efficiency would be horrible. The noise would also be terrible.
I could use 4xAA and LDOs, but steping down to 3.3V from 6V doesn't sound like the good way to do it.
So I could use 3xAA (4.5V) with a LDO to provide 3.3V and a charge pump to provide 5V, but then :
- the LDO will fail under 3.4V, wasting around 20% of the AA batteries. So maybe I should put the LDO after the 5V charge pump... or find a way to do that only when the LDO fails...
- charge pump arn't exactly low noise. Maybe I should use an LDO after it to get rid of the noise...
I'm starting to have more questions than answers. What is the correct way to solve this beginner electronics engineering problem ?