Hi,
  A few of you will probably remember my homebrew battery charger project.
I've now got enough spare time to make a serious attempt at implementing it.
Problem is, information on SMPSUs seems to be a bit thin on the ground, and
what little I can find is full of formulae and equations that make little or
no sense to me. Can anyone suggest a site that covers the basics of SMPSU
design? I seem to recall someone posting a link to something along these
lines, but I can't find the link in my "Interesting PICLIST postings" archive
:(

  I'm thinking of an inductor-based step-down, probably with PWM control
though I haven't made a firm decision yet. I've found a few Microchip
appnotes on PSM (aka PFM) control, but nothing on PWM. What would be really
useful is some info on the advantages/disadvanteges of PWM vs. PFM, and why I
might use one over the other.

  I'm also after some info on PID control (I was planning to use PID to keep
the output voltage/current stable) - the Wikipedia article was quite
informative, but tuning a PID loop seems to be something of a black art. Does
anyone here have any hints they can share?

  I'm probably going to use straight linear control along the lines of "Vout
just jumped up by 1% of full scale, so kick the duty cycle down by the same
amount" for the first-cut of the code, but I'd like to use PID later on (it's
reputed to be more stable than linear control).

  At this point, any info would be much appreciated.

Thanks.
-- 
Phil.                         | Kitsune: Acorn RiscPC SA202 64M+6G VF+UniPod
philpem@dsl.pipex.com         | Cheetah: Athlon64 3200+ A8VDeluxeV2 1G+180G
http://www.philpem.me.uk/     | Tiger: Toshiba SatPro4600 Celeron700 256M+40G
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