TI Laptop PSU Chip

dug1967 · 01-16-2004, 11:04 PM

It was over a year ago but somebody posted about a surface mount chip from TI (Texas Instruments) that was basically a Laptop PSU chip..... It took Battery voltage input (12VDC I think) and produced 3.3VDC, 5 VDC, 12VDC, etc... basically all that was required for an ATX PSU....

Now it was insufficent amperage for what a Car computer needed, and it also required supporting circuitry.... but it appeared to be a great starting point...

I thought so much of it at the time that I got samples from TI.. ones that I can't find now... crap...

But I have two question... does anybody know what chip I am talking about? also assuming it gives what we need, but with insufficent amperage, why not run several in series to up the amperage????

Any ideas?

Rob Withey · 01-17-2004, 05:39 AM

Was it the TI ISR series? I use a TI PT5071 and a PT6625 to power my system.

dug1967 · 01-19-2004, 08:07 AM

No, that doesn't look like what was mentioned before, but WOW, is that by chance your entire power supply?

I will check out those two chips you mention.

Rob Withey · 01-19-2004, 08:13 AM

Yep, that is my entire power supply (including remote on - no relay needed). It's low power by most people's standards (5V @ 5A, 12V @ 1.5A), but is very efficient and small in size (which is good, since my entire carputer is small).

Rob

dug1967 · 01-19-2004, 01:02 PM

That is cool Rob,

I looked through the specs on those chips.... pretty nice, but as you said they are low amperage....

I looked through the TI site and also Maxim and can't find a similar chip that would have

Vin(min) = 8 VDC
Vin(max) = 15 VDC
Vout = 12 VDC (+/- 5%)
Iout = 5 A max

Has anybody seen such an animal. There is some 5 VDC out chips that give 5 A, but no 12 VDC out that I have found.

VWTronics · 01-19-2004, 04:00 PM

Try this one:

LM3478

http://www.national.com/ds/LM/LM3478.pdf

dug1967 · 01-19-2004, 10:20 PM

Thanks for the suggestion VW, but I am a little confused on the LM3478. First off the Web Design on the National site doesn't seem to function right for the given inputs...

Vin(min) = 8 VDC
Vin(max) = 16 VDC
Vout = 12VDC
Iout = 5 amps

I put that in at first and it says "use the LM3478", so when I got to "do the desgin, it comes back and says nothing meets my requirements, please use LM3478....

Running in circles... I read the entire data sheet on the LM3478 and I all I see is 5VDC at 5amps and then later 12VDC at 1.2 amps..... Can the LM3478 put out 12VDC at 5 amps????

Sorry to be a pain in the ***, but this circle is getting boring...

Also what about the LM2587? I kind of get them impression that will top out at 1.2 amps also....

But thanks for the help.... it is much appreciated.

VWTronics · 01-22-2004, 02:29 PM

Bump