ITPS Regulation

**Pudge** · 01-26-2004, 05:12 PM

Originally Posted by none

The regulator, however, is poorly suited for automotive use.

Agreed (To a point, depending on the needs of the user), but what else do we have to regulate 12v DC? I'm not questioning your judgement, I'm looking into other options, and want to see what's out there.

**MikeH** · 01-26-2004, 09:00 PM

Ricky, Shakes.

It still puzzle me why the ITPS/PW70 cant survive a crank when you dont even use a 12V device

If you look at the PW70 specs for input voltage tolerance...you'll find it's +/-15%, or 10.2v to 13.8v. Your battery must be going below in the 10.2 on crank.

**Ricky327** · 01-26-2004, 11:25 PM

Thanks for the info MikeH.

But from what I understand the PW70 does not regulate the 12V rail...all it does is pass the input out to the 12V rail unregulated and into the motherboard. The 3.3V and the 5V rails are regulated using this 12V input before being fed to the motherboard.

So if the PC setup does not require any 12V rails then all thats needed are the 3.3V and 5V rails? make sense so far. But surely to regulate these two low voltage rails cant be needing 10.2V atleast from the inputs...a standard linear regulator such as the 7805 only need about 7-8V for it to regulate a 5V out of it and therefore should survive a crank.

The sproggy is supposed to survive a crank and I do believe that since the 12V rail is stepped up from the regulated 5V.

There has been a discussion here before about building a bare minimum PSU. A +5V, +3.3V, +5VSB regulated PSU...and no +12V. Building this design based on a switching regulators should easily output 5A or more with a supply input down to 7V or so...therefore surving a crank. I dont know if someone attempted the idea but it should be easily achievable with the help of WEBENCH.

**none** · 01-26-2004, 11:59 PM

Originally Posted by Pudge

Agreed (To a point, depending on the needs of the user), but what else do we have to regulate 12v DC? I'm not questioning your judgement, I'm looking into other options, and want to see what's out there.

I don't think these PSUs (pw60/70a) are suitable for car use at all if you need 12v out of them. For me, the best solution has proven to be a Sproggy, but I understand some people are not comfortable with a soldering iron.

Originally Posted by Ricky327

The sproggy is supposed to survive a crank and I do believe that since the 12V rail is stepped up from the regulated 5V.

That is only on Mastero's redesign (3.0) of the Sproggy (which doesn't seem to work for most who have tried it.) The actual Sproggy design (2.5) and Mastero's versions of it (up to 2.8+) use a LM2587 flyback regulator for the 12v. These are the ones that have been proven to survive a crank by many past users of this forum.

**Ricky327** · 01-27-2004, 12:05 AM

Ok thanks for making this one clear. I just know there many redesigned sproggys out there

**NJay** · 01-27-2004, 09:35 AM

One thing I noticed when I was trying to work out power consumption for my Eden-800 is that even with NO 12v components selected the MB itself still has a 0.11A drain on the 12v line.

http://www.mini-box.com/powersimulator.html

Either the calculator is wrong or that the MB does use the 12v line

**craigyb** · 01-27-2004, 09:39 AM

Maybe I'm confused here, but aren't the ITPS and the PW70 supposed to be used together to survive the crank.

Craig

**Linus** · 01-27-2004, 10:25 AM

Originally Posted by NJay

Either the calculator is wrong or that the MB does use the 12v line

Could that be for the fan connectors on the motherboard? The Epia 5000 (the one without a fan on the CPU) is listed as using ~half as much on the 12-volt line, so maybe they're counting for both motherboard connectors.

**Rob Withey** · 01-27-2004, 10:29 AM

Originally Posted by craigyb

Maybe I'm confused here, but aren't the ITPS and the PW70 supposed to be used together to survive the crank.

I think you are confused.

Afaik, the ITPS uses a linear voltage regulator with significant headroom required to maintain a 12v output. It doesn't offer (afaics) any reboot protection during cranking. The only way you are going to solve this problem with any success is to make your power supply tolerant of input voltage drops such that it can maintain the 12v line.

**adamis** · 01-27-2004, 02:44 PM

Making the ITPS surviving a crank is going to require a second battery. If someone actually does get it to survive a crank without a battery I would like to know how they did.

I gave up on trying to make the thing survive a crank months ago because I was having problems with the small battery not getting charged. Anyway, the moral of the story is after two months I have had only one time where it would have been nice for the system to survive a crank... So it wasn't and isn't really worth my time to try to fix something that I never really use anyway.