DC DC booster inductor calculation's

[supak111]

Hey guys I'm trying to use this tiny DC DC booster yx8018 to boost 2 AA batteries when they are dying to keep the output voltage to minimum 2.5v (like joule thief circuit) but not sure how to calculate the size of the inductor needed to achieve 2.5v output.

Here is a simile diagram for what I'm trying to do from a garden solar light, my circuit just wont have the solar panel in it. Below circuit uses a 220 uH inductor to boost a low 1.25 volt NiCd battery.

 

[Harald Kapp]

The required size of inductor for different LED currents is staed in the datasheet.

 

[supak111]

I'm not powering an LED sorry I should have mentioned that. I will have to check the current of the device, hopefully it doesn't vary a lot. If I had to guess 100 to 150 mA at 3v

 

[Harald Kapp]

That chip is good for 30 mA only acc. to the datasheet. For 100 mA you'lll have to check other options (chips).

 

[supak111]

Ahh ok thanks Harald. I'll check on the current first, it might be 30mah