What is the best method to convert 1.2v (or 2.4v) to 5v supply?

[hoekeat]

Hi All,

I am newbie in EE projects. Currently planning to do something with Raspberry Pi and other similar stuff and wish to create a compact mobile power pack. Am thinking of using generic rechargeable 1.2v AA battery, maybe 1 (1.2v), or 2(2.4v) units of it. As Rasp Pi and a lot of devices uses 5v battery, i am planning to create something that can convert either 1.2v or 2.4v to 5v battery. Any direction is much appreciated. Thanks

 

[etmabreu]

Use some kind of switched-mode power supply like these:

https://pt.farnell.com/jsp/search/b...etricAttributeId=&prevNValues=601+2024+202797

 

[hoekeat]

found out about MC34063A, but it take input of 3v and above. Is there any IC that is similar, but takes 1.2v or 2.4v?

 

[sky_123]

Linear Technology have lots of nice devices that will do this. Bear in mind that many boards designed for 5v power supplies may not have been designed for portable use so their power consumption may be high so a battery may not last for longer than a few hours possibly.
If (say) a board requires 5V 100mA, then you'll need a battery that can supply at least >200mA at 2.5V, and proportionally higher at 1.5V, depending on the regulator efficiency. Probably best to use 2.4-3V if you can rather than 1.5V, if you are planning to step-up to 5V.
An example LT device is LT3525, but they have many dozens more.

 

[BradtheRad]

I have a bright white led flashlight that runs on a single AAA battery. The brand is Bayco.

I use a rechargeable in it. Lasts upwards of half an hour.

Two bright whites are lit up by the step-up converter inside. It can operate even when the battery is down to 1V or so.

I suppose it is a 'joule thief' type of converter. Technical name is blocking oscillator, using a transistor.

Just goes to show what is possible.