`NEW' Small DC-DC ATX Power Supply

**Casper** · 07-26-2002, 09:34 AM

ok.. i havent tested mine, but it was a warning to everyone that for some cars it may not be suitable... ive heard of some dropping (or more like drooping) to 8v. Have to dig out the multimeter and test mine now...

**eugenen** · 07-26-2002, 11:49 AM

I put my simpson 260 VOM across mine, nice big needle to see the drop.

Got my ISR's today! Now I realy see the advantage of these. I looked at the size in the spec sheets, but these are a lot smaller than what I was expecting. They are about the size of a 9v battery, shorter, but a little wider. I was going to have to add a second PCB inside my case for linear regulators, but with these I don't have to.

**CrazyLittle** · 07-26-2002, 01:11 PM

Originally posted by Casper
ive heard of some dropping (or more like drooping) to 8v. Have to dig out the multimeter and test mine now...

that's an easy fix with a small tank circuit.

**eugenen** · 07-26-2002, 05:20 PM

Or a big cap, used to have to replace them on the terminals in the fedex trucks all the time. Now why didn't TI make a 12v in their ISR line?

**CrazyLittle** · 07-26-2002, 05:53 PM

ummm... that's exactly what a "tank circuit" is: a big cap.

**eugenen** · 07-26-2002, 06:23 PM

Not unless the def has changed since I took electronics. A Tank circuit will have a cap and inductor, values set to a resonant frequency to osciallate.

**eugenen** · 07-27-2002, 11:03 PM

I was looking around TI's web site looking for something I could use for the 12v line. I haven't found it yet, but did fine a lot of other ISR's. Here is a product selection page http://www-s.ti.com/sc/psheets/sltt063c/sltt063c.pdf .

How about 5V@13A no heatsinks? (PT6724)

**Casper** · 07-28-2002, 09:59 AM

these parts would be useless on a car system (PT67xx) as the maximum voltage input is 13.2v DC, while most cars (while switched on) should run at just over 14v... your also unlikely to need 13 amps on each of the 5v and 3.3v lines...

as for the 12v line, im looking at hooking up some parallel components... 2 or 3 should do, going to test the PT5071 (1.5A) next week.

**eugenen** · 07-28-2002, 10:54 AM

You could always stick a big zeener in front of themto limit the voltage. I'm probabally going to do tha on mine anyway as a surge protector. Where can you order the PT5071? My system only needs .29A on the 12v line and the hdd runs off od the 5v line only (lapotp hdd). So this would work fine for me. Its not in digi-key or mouser though.