3 NiMh (3-4.2V) to 3.3V, or use 2 and step-up?

[Zedman]

I would like to have 3 - 3.3V max from NiMh AA batteries.
I have 3 of them in serial but as they 1.2 V each they make 3.6V and 4.2V if they are fully loaded.
I want to run 2 MCUs which work from 3 - 3.6V from it so I need to regulate the voltage to that interval.

But what's the best and cheapest way to do this? Just using a 3.3V zener would do the trick, but does it affect the battery life?

Would it be better to use just 2 batteries and use a Step-Up DC-DC?

thanks
Zedman

 

[Audioguru]

A zener diode wastes a lot of power when the source voltage is high.
A low-dropout series regulator set to 3.6V and an input of 4V or more will work.
A voltage stepup circuit kills the battery quickly.

 

[hock]

if your load current is low (few tens of mA) you can use 2 cells and a buck boost regulator. look at maxim and linear tech web site.
hock

 

[Zedman]

I decided to use a 3V low dropout regulator. It has only 300mV dropout@150mA.