Switching power for PC in cars

[Frank Schmitt]

Kalle Pihlajasaari wrote:
> 
> If one really wants to build ones own one can use some of the
> SIMPLE SWITCHER (R) power converter ICs from National Semiconductors
> which I think are the ones use in the expensive PC-104 supply that
> I have used and they are VERY simple to use, I plan to try it out
> and they look like the right answer unless they are too expensive
> for production volumes.  They require a single IC in a TO-220
> 5 lead style, an inductor, a Schottky diode and 2 capacitors.
> Just that to get 5V at 3A from 9V to 35V in.  You will need to add
> primary surge, reverse voltage and noise filters but this would
> always be required.
> 
> Part number that is mentioned above is the LM2596T-5.0
> 

I'm new on the list but have some experience with these, so I thought
I'd de-lurk. As part of a project here at Mudd we're putting together
a handheld computer using a Megatel PC-104 compatible (Eurocard)
computer, an off-the-shelf LCD, and three of the simple switchers to
do +12, -12, and +5 from a 14.4 volt battery (two stacks of NiCds).

A couple of notes on these: First, you can unify the input filter
capacitor from, say, three of these into one (simply summing the
capacitance would do the trick). 

Secondly, they offer a free DOS package called "switchers made simple"
which removes absolutely all of the guesswork from designing these. 

Finally the DC-DC converters mentioned previously would likely be
cheaper than this, although I can't imagine they would be in OEM. 

-Frank

 -- Frank Schmitt -- Harvey Mudd College -- http://www3.hmc.edu/~fschmitt --