For a application some Zigbee End Device modules (based on CC2530) are used as simple Switches and they should be powered by batteries. Now I was wondering are there some considerations in hardware design phase to get the best use out of a battery?
Like I have seen people put a capacitor in parallel with the battery to sustain battery life! Should I calculate this capacitor or any pretty large capacitor would be fine? (I know there is the leakage)
Plus which kind and how many batteries are usually used in applications like mine? (CC2530 operating supply is 2~3.6V)
I was thinking about using 2 (in case of powering directly from battery) or 3 (in case of using 3.3V LDO after battery) AAA 1.5V NiMH batteries. What do you think? Is there any better options? (of course cost and space is very important!)
I have another question. Should I put a LDO regulator after the battery or is it better to power the module directly from battery and without LDO?
Considering that CC2530 works between 2 ~ 3.6V and if I put a 3.3V LDO then battery does not power the module when it fells down to 3.5V and will waist a lot of its capacity (LDO does not work correctly anymore)
On the other hand I know if I use LDO after battery and get a lower voltage then current consumption of the CC2530 would decrease considering its operating current is a function of its input voltage.
I'm afraid if I use a battery directly then there would be some sort of instability in the performance of the module. I'm not sure though.
So to sum it up I need advice on:
1- Which kind and how many batteries
2- Using or not using LDO
3- Parallel capacitor with the battery
for a long run time and good performance.