Most of the eval modules are around $50, so if you're going that way
then you'll end up paying about that much.

TI has a few parts in the area you're interested in, with $50 eval
modules available at digikey, TPS6104x, TPS6108x.  Efficiency is about
the same, which is typical for this type of boost conversion.

There are also a bunch of $15 TI boost converter modules, such as
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=3D296-1968=
2-ND

Those that I've seen, such as the above module, only go up to 15V, but
if you pull the datasheet on the chip they are using you may find it
has additional range with few modifications.

-Adam

On Thu, Aug 20, 2009 at 9:04 AM, Tony Vandiver<tony@traceelectronics.com> w=
rote:
> Sorry, forgot the tag -
>
> =A0 I need a quick and dirty way to power an LED backlight that has typic=
al specs of 16.5V and 40mA. =A0My source is a LiPo battery that can be anyw=
here from 2.8 (discharged) to 4.2V (being charged) out. =A0Ideally, I'd lik=
e to find a demo board (that I can get in house in a couple of days) that I=
 can wire into my existing design for prototyping and presentation to a cus=
tomer, and then adapt the demo design into the artwork after it's proven. =
=A0(90% efficiency would be great, but not a must). =A0I'd love to have a M=
icrochip solution, but even they use a MIC2289 (Micrel) part on their LCD d=
emo board to do this. =A0I'd like to have a regulated current supply, but t=
here is the possibility of outputting 18V or more from this switcher to a c=
urrent regulator that I already have populated on the existing design - jus=
t decreases my overall efficiency that much more. =A0This one has an adjust=
able output
> which is nice, but is kind of pricey at $50 each (I need 5 pieces - look =
at the bom - it's probably a 95% margin over materials) and only around 86%=
 efficient at my point of interest :
>
> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=3DLM2703=
EV-ND
>
> Thanks,
>
> Tony
>
>
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