Thread: found plans for 86W ATX DC-DC

http://www.ednmag.com/ednmag/reg/1994/020394/03df1.htm

thought this artical might be of interest to some..

Originally posted by Jeff Mucha:
I tested my supply at 3.5 amps (on the 12v output) for 5 minutes with a 12 volt input and it did just fine

Jeff,
you said you were using the lm2587.
This is the same part as in the sproggy supply.
Do you have a design in your psu which is similar to sproggy's 12v part? (and are you using the t6 (Q4339-B) )

If so, the sproggy supply should also be able to supply such current as your supply does.

Greetz

Yes I am using the LM2587/8. No I am not using any transformers. I have 3 inductors of very low value. You can wind the coils yourself with 18 - 20 gauge wire. The coils range from 10 - 30 uH. My supply is similar to the sproggy supply. I don't use any maxim parts and my inductors are smaller, but my current on the 12 volt supply is significantly higher and I don't cut into the 5 or 3.3 volt lines to derrive any thing else. I have a switched capacitor network generating the -12 and -5 operating at 100 khz. This is similar to what a max 232 does, only mine puts out more current.

The sproggy supply is a straight from the databook implementation of the 2587. He didn't change anything. The sproggy supply is limited by that transformer, the catch diode, and the caps he used. That is why it is rated at 1.2 or whatever current. I bet you could get 2 amps out of it but that would be a stretch.

Jeff_