How could I make the ultimate car PC powersupply and what should it do?

**kiddigital** · 11-14-2001, 03:41 PM

I have been reading and thinking a lot lately on how I could approach the power supply problem for my car PC.

There are a few issues to consider:
1- ATX power supply
2- -5v needed for serial ports (IR, GPS and mobile phone functionality)
3- +5v Power good signal for most boards
4- Automatic start-up and shutdown (using the available 12V ACC or ignition line in the car)

I’ve seen several product and combinations of products to achieve one or more of the given goals. For my ultimate setup, I think I will need all 4 features.

The ATX part is not the biggest issue. Several products or homemade products are available of which some of them have a –5v or +5v Power good. Both seem to be rare (Any suggestions anyone ?

).

The startup/shutdown seems to be more difficult. With my current knowledge I would go for a solutions that uses the ACPI S4 functionality, also called ‘hibernation’. Problem is that only a few boards support the S4 function. Also an issue that not all software or other peripherals (like a good soundcard) support this function. If good S4 supporting hardware can be found, than some kind of facility has to be made to trigger this feature through the ATX power connector and this facility itself has to be controlled by the ACC or ignition switch of the car. It should also incorporate a small delaying mechanism to prevent startup/shutdown being triggered several times when you try to start the car.

So as you can read, I still haven't found a satisfactory solution to achieve the 4 given goals. I am open for any suggestion to help me out here.

**jshrieve** · 11-14-2001, 05:23 PM

keypower ATX 12VDC DC-DC PS will satisfy #1 #2 and #3.

#4 can be solved with Jeff Mucha's shutdown controller. http://skylab.org/~chugga/mpegbox/shutdown/overview.jpg
paypal him $23 to get one.

Details on how the shutdown controller works: http://www.mp3car.com/cgi-bin/ultima...c&f=9&t=000203

**Telek** · 11-14-2001, 09:07 PM

Check out my website (below)

I just created a Sproggy v2.7 and v2.7.2 power supply that'll give up to 13A on the +5V line, which should be enough to handle everything (this is ATX as well). If you use the 2.7.2 design you can easily integrate the MPEGBOX shutdown controller into the unused portion of the PCB! This'll satisfy all 4 of your requirements

**leon** · 12-03-2001, 02:47 PM

Originally posted by Telek:
<STRONG>Check out my website (below)

I just created a Sproggy v2.7 and v2.7.2 power supply that'll give up to 13A on the +5V line, which should be enough to handle everything (this is ATX as well). If you use the 2.7.2 design you can easily integrate the MPEGBOX shutdown controller into the unused portion of the PCB! This'll satisfy all 4 of your requirements

</STRONG>

Hi, just curious about where you obtained your components for building your 2.7 PSU since you’re in Canada too…

Also, what LCD monitor do you have?

Thanks,

**Telek** · 12-03-2001, 02:56 PM

Well National sent me "evaluation" parts at $0 cost to me and with next day priority delivery... yeowtch!

Coilcraft wanted me to pay $5/part (4 parts) and then stuck me with a $44 bill. I'm going to go yell at them.

Maxim also sent me evaluation parts free of charge. Those took about a week or so to get though.

However since I'm redesigning a newer and more powerful supply, I might not even use those parts. We'll have to see once I get home. (I haven't built it yet).

As for the LCD, I have a 640x480 10.4" VGA input TFT at 200nits made by Datalux. I think it'll be fine.

**leon** · 12-03-2001, 03:00 PM

HOw do you get those coils now? Coilcraft wants $20US for shipping?!
http://www.coilcraft.com/cfm/MP3.cfm

**leon** · 12-03-2001, 03:03 PM

HOw much more powerful? ie total wattage?

**Telek** · 12-03-2001, 06:27 PM

looking like it'll be 13.5A on each of the +3.3V +5.0V and +12V rails. 300W total.

**JoeShmo** · 12-04-2001, 12:03 AM

When I was doing the 'ol search for the elusive 12v input ATX power supply, I came accross a design by intel for exactly what everyone seems to need. It seems to no longer be on thier site (well, I cant find it). But I do have the PDF.
http://www.tcenet.net/joeshmo/atx
the design is the 27354901.pdf file. The rest of the files are schematics for how to use the various chips.

I would build a few of these myself, but this goes a little beyond my basic understanding of circuit design, plus I don't have the time to experiment much.

So here it is.. take it and run with it. If someone makes some of these, and they seem to work good, let us know! I'm sure someone can make some money. Some people are selling ready-made "sproggy" supplys for around $130!! Thats almost as much as those other ultra high priced ones that people are doing the group buy on.