"Christopher Ott" chrisott at ottelectronics dot com wrote in message
...
I've been using the National "Simple Switchers" with good results for
awhile, and would like to take a step beyond the usual methods of setting
the output voltage. I typically use the fixed voltage versions of the
LM2676 with a resistor in series with R2 to increase the output voltage
when the predetermined +5 or +12 needs adjusted. But now I'd like to
control the output voltage using a microcontroller. I'm pretty sure I
could get this done by using the adjustable version which does not have R1
or R2, and placing a digital potentiometer in place of R1 with an
appropriate value of fixed resistor for R2. However, I have a spare
channel from an offboard 5 volt D/A which would be cheaper and easier from
a BOM standpoint. I was hoping to get it done with some spare R to R
opamps which are also available.

My analog skills have gotten a little lazy over the years and I'm having a
tough time thinking this one out. I guess the bottom line is that I need
to control the feedback current from the switcher output using a 0-5v DAC
output.

Any ideas? I would tend to think this has already been done somewhere by
someone...

Chris


How about an LM2636.

Bob