2XAA boost converter

[Mark]

Hello all,

I need a boost converter to convert 2 AA batteries to 5 volts at 100 ma or
so. Does anyone have a favorite chip? Efficiency is not critical, regulation
is not critical. I would like to be able to drain the AAs to .9 volts, so
1.8 volt minimum input voltage would be nice, though I'd settle for 2.0, or
even 2.2 if nothing better is available. Thanks for any assistance.

Mark

 

[Roger Hamlett]

Hello all,

I need a boost converter to convert 2 AA batteries to 5 volts at 100 ma
or
so. Does anyone have a favorite chip? Efficiency is not critical,
regulation
is not critical. I would like to be able to drain the AAs to .9 volts,
so
1.8 volt minimum input voltage would be nice, though I'd settle for 2.0,
or
even 2.2 if nothing better is available. Thanks for any assistance.

Mark

100mA, is quite high. Equates to 500mW, and about 300mA from the batteries
when they are getting reasonably discharged. If you can trim your power
needs to about 200mW, then consider the Texas UCC39413. For your higher
power requirement, consider the TPS61070. Maxim do some quite 'nice' ICs
for this sort of job, but they suffer from availability problems, unless
you want to buy a reasonably large quantity.

Best Wishes

 

[Mark]

Thanks, Roger. The 100 ma was really a 'wish' number. I can make do with
less, though I'm still not sure of the exact requiremnt. One of the modules
I have to power is an audio amplifier driving a tiny speaker, and I don't
know yet how much power I will need there for adequate volume. I suspect I
will modify what 'adequate' means based on what I can provide. The rest of
the circuit will be under 10 ma at 5 volts.

Mark

 

[Lostgallifreyan]

One of the modules
I have to power is an audio amplifier driving a tiny speaker, and I don't
know yet how much power I will need there for adequate volume.

Hard to quantify, but easy to add a bigger capacitor on the output as a
reservoir. Still got to watch it's surge on switch-on doesn't damage the
charge pump IC though.

 

[Homer J Simpson]

Thanks, Roger. The 100 ma was really a 'wish' number. I can make do with
less, though I'm still not sure of the exact requiremnt. One of the
modules
I have to power is an audio amplifier driving a tiny speaker, and I don't
know yet how much power I will need there for adequate volume. I suspect I
will modify what 'adequate' means based on what I can provide. The rest of
the circuit will be under 10 ma at 5 volts.

50 mW average is quite loud.