3.7v to 5v

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- 29th January 2007, 22:21
Sphere

3.7v to 5v

I would like to use a 3.7 volt lithium iron battey in my next project, but I need a 5 volt supply at 500mA so I need to convert 3.7 volt to 5 volt. Anyone got any schematics. Ive pullled apart a psp power pack to see what chip is used, but Im unable to source the chip used in the pack.

Sphere.
- 29th January 2007, 22:39
Archangel

Charge pump

Check with MAXIM, they sell lots of different charge pump ICs just for this.
- 30th January 2007, 05:26
mvs_sarma

Quote:

Originally Posted by Sphere

I would like to use a 3.7 volt lithium iron battey in my next project, but I need a 5 volt supply at 500mA so I need to convert 3.7 volt to 5 volt. Anyone got any schematics. Ive pullled apart a psp power pack to see what chip is used, but Im unable to source the chip used in the pack.

Sphere.

Hi,
you can try the old and reliable MC34063A
datasheet at www.alldatasheet.com

off late you get MAX172x series in SMD and it is good. you may download a datasheet for max1722 and 1724., i fear it may not, give 500mA.
- 30th January 2007, 17:53
Sphere

Thanks

The MC34063A looks good to me, just over a quid to buy. Just had a look on maxims site and theres lots of choice and all readly avalable.

Thanks both Sphere.......
- 30th January 2007, 17:58
Ron Marcus

I believe a coil based boost converter is better than a switched capacitor type for higher currents. The down side is they tend to be noisier in the RF spectrum, and the coil is going to be fairly substantial in size to handle the higher currents without too much resistive losses, or going into saturation.The higher the switching frequency, the smaller the inductor, but... the more possibility of interference.
Ron