DIY Switched Mode PSU?

Question

Anybody know of an IC for making simple switched-mode power supplies? I need to drop 12V (from a lead-acid battery) to 5V, at up to 2 amps. Would be nice to be buildable on Veroboard, and the fewer coils I have to wind the better!

I'm sure something like this must already exist for automotive use, as engine management systems and the like are getting more complex and needing more power than can comfortably be dissipated by a simple 7805-type linear regulator.

Answer 1

Go to

http://www.national.com/analog

and check out their 'simple switcher' line.  They work well (I've used a bunch of them over the years) and they don't seem to have any bad habits.  Also, all of their applications circuits use nice 'standard' parts that you can find at DigiKey or Mouser.

The part you're looking for is the LM25576.  Tons of application data and you can use their 'webbench' analysis software on-line for free. It kinda takes all of the fun out of designing SMPS's.  Back in the old days, half the fun was watching things flash and vaporize a time or two before you got it right ☺

If you run into any serious problems, give me a yell ☺

HTH,

Doug

Answer 2

I would like to know how to learn what you are asking.   You sound saavy.

Typically I would be thinking about using resistors and a voltage divider network that would leave me with a 2.5 ohm, 5 volt,10 watt resistor to supply the circuit you are mentioning with a 3.5 ohm, 7 volt, 14 watt resistor in series  or a 15 watt auto transformer that had a tap or allowed you to set the tap at 5 volts.  

I am showing my ignorance by trying to answer your question probably.