Hello , i made this pcb just only to supply an mp3 player, that use only one battery 3AAA ,but in 2 hours battery was run out. I used rechargeable batteries ,but without good enough result. So, i was searching around for something better and i found the best!!
And yes ,as most times i do,i found the best solution, it is lp2951. It’s a IC, with extremely low quiescent characteristics make it ideal for using in circuits with batteries. In a few words, input is 2-29 volts ,output is <<adjustable>> 0-28 volt .And the most extremely is Low Dropout 380 mV at 100 mA !!!
I must admire that all those are in theory, in practice drop out is around 800mV at 80 mA but how cares indeed ,it is almost ideal . You can view all those in manual and much more that will help to make your own regulator
The schematic is this
The very easy equalization to reach theε desirable out voltage is blow
where Vref is the nominal 1.235 reference voltage and Ifb is the feedback pin bias current, nominally 20nA.
So, leaving R2 100k ,we can experiment changing only R1.
In my situation i need around 1.5 volt, so work it out as R1
and it should be 22k.
Take care, there are 3 bridge to the upper side
In conclusion,it play maaany hours!! I don’t know exactly how many because i forgot when i charge it !!!!