Lpc2000

Unfortunately the source that I am using for most of my components doesn't 
carry that regulator.  However your idea got me thinking.  From another 
suggestion that was posted, the TPS61041 regulator chip is about 1/2 the 
cost of the TPS61041, provides much higher current, and requires a similar 
number of external components (and has a feedback line).  Would the same 
method of adding a 100k resistor to the feedback line and to a PWM output 
on the micro work here?  I don't see why not.  Can you see anything wrong 
with this idea?

Thanks!

-- Sean

At 06:01 PM 1/14/2006, you wrote:
>Herbert Demmel wrote:
>
> >Dear Sean,
> >
> >we had to deal with this issue on our unversal LCD controller boards - see
> >at www.demmel.com - and we solved it as follows: We took the (very cheap)
> >switcher IC TPS61041, which can produce up to + or -28 volts and made the
> >output voltage variable by feeding a PWM controlled voltage of 0...5 (can
> >be 0...3.3 volt as well) volt via an 100k resistor to the FB input. You
> >only need the TPS61041 which only costs about 1.5 US$ (single pieces) and a
> >ready to use Murata 10uH LQH32CN100K33L which costs less than 50 cent
> >(price is also for single pieces). You only need a few passive components
> >and a shottky diode like MBR0540T1 (about 40 cent) then and everything is
> >working fine. You get all parts at www.farnell.com, TI has good reference
> >schematics, you only have take care to use X7R capacitors. The TPS61041 can
> >be supplied with voltages between 1.8 and 6 volts.
> >
> >
> >
>Interesting technique.  I also was thinking PWM followed by a filter,
>but I was thinking that you would need to switch the  output off/on.
>Your solution to modulate the FB line is a much cleaner one! Cool!
>
>Regards,
>
>TomW
>
>
>
>--
>Tom Walsh - WN3L - Embedded Systems Consultant
><http://openhardware.net,>http://openhardware.net, http://cyberiansoftware.com
>"Windows? No thanks, I have work to do..."
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