1.2V to 5V@100mA max mini power supply

[mabauti]

I want to build this, preferably with high efficiency.

any idea?

 

[bananasiong]

Search boost regulator or boost converter from Linear or Texas Instrument.
What's your input? An AA cell? 100 mA output current seems too high for that.

 

[mabauti]

sorry bananasiong, could you be more specific about an IC or circuit/diagram?

 

[audioguru]

100ma at 5V is 0.5W.
If you have a 1.2V rechargable battery cell and you boost its voltage to make the 5V then the current from the 1.2V cell will be more than 0.5W/1.2v= 417mA. A 2500mAh AA Ni-MH cell will last for less than 6 hours.

 

[bananasiong]

Can the little AA gives the output current of 400 mA?

 

[Gayan Soyza]

OMG why not! Now available 2700mAh AA NI-MH cells.

 

[mvs sarma]

A MAX1724 will work fine
Datasheet attached

 

[audioguru]

Can the little AA gives the output current of 400 mA?

Hi Banana,
Look at the datasheets for battery cells at www.energizer.com:
1) An alkaline AA cell has an internal resistance of from 150 milli-ohms to 300 milli-ohms when it is new. Then its max current (into a short) is 10A or 5A.
2) A Ni-MH AA cell is shown to have a good output for 20 minutes with a 5A current drain.
3) My electric RC airplane's motor draws about 12A from its Ni-MH AAA cells.

 

[bananasiong]

Hi Gayan, I'm not talking about the capacity but the output current

Thanks audioguru, I just recalled that I've used a few NiMH AA cells in series to run a DC motor at a few Amperes.
Why not only 400 mA

 

[mabauti]

Thank you all. I'll try that suggested by mvs

see you

 

[Overclocked]

If you need more current give the MAX1703 A try.
**broken link removed**

 

[erwin yudha]

DC-DC Converter: 1.2v(Ni-MH AA cell) to 12v@15A, any body can help me? thanks

 

[Sceadwian]

12V 15 amps?
That's 150 amps at 1.2 volts asuming 100% conversion effciency, which will never happen, you'd never make a parallel NIMH battery bank that large.

 

[audioguru]

Don't be ridiculous. Stepping up the voltage steps down the current.
A Ni-MH AA battery cell might be able to provide 1.2V at 2A for a couple of seconds but you are stepping up its voltage which steps down its current to only 200mA, not 15A.

If you want 12V at 15A then the 1.2V source must provide 150A.

Simply calculate the power. The battery is 1.2V x 2A= 2.4W. But you want 12V x 15A= 180W. You need 178 more AA cells.

 

[erwin yudha]

thanks all

 

[Hero999]

Agreed, it's a silly idea.

You're better off connecting ten D cells in series but even then, they'll last of less than an hour.

If you need voltage regulation connect 12 D cells in series and use a buck converter.

Make sure you use real D cells, not AA batteries with extra padding.

For a sensible option use a lead acid battery or if it's too heavy go with lithium but you need to be careful charging it.