Thread: ITPS Regulation

Originally Posted by BigRedBee

Does anyone know what's gonna happen when I powerup my desktop IDE CDrom drive and feed it an unregulated 12V directly from my car battery (aka 14.5v) ? I'm gonna try it this weekend on a spare drive I've got laying around, unless someone screams "NOOOOOoooo".....

YESSSSSSSssssssss..... go for it....

cus I want to know what happens also and I don't have an extra Hard Drive to fry..... (if that happens, I am not saying it will)

Your sacrifice will be appreciated by all..... God be with you...

My name is Andrei, one of the people that designed the ITPS.

OK -- so here it is:

-ITPS was designed to work with the engine running
-ITPS was designed to 'stay on' even when the engine was stopped (watch your system load!)
-ITPS *was not* designed to survive engine re-starts.

There are several things you should know about the mini-ITX boards and car systems, this will help you avoid some problems:

1) NEVER use 3'5" drives on your car. They are not designed for shock and they use the 12V rail for motor spinup (2.5" drives use only 5V). They also suck a lot of power...

2) If you system configuration exceeds 60Watts, bypass the LDO on the ITPS. Mini-ITX boards can take anywhere from ~10V to 18V on the 12V rail. As a matter of fact the 12V rail in a mini-ITX system is used only for FET drive and fans (if any).

3) You can safely bypass the LDO (the LM-1084) if you are not using 3.5" drives in your system. This way you can drive insane amounts of current through the ITPS. You will also get rid of the ~1V voltage drop on the LM-1084.

It is very hard to step-up 12V (for situations where your car batteries dips below 12V). You would have to fly-back the input voltage to something like 6V and then step it up to 12V, this is usually highly inefficient.

Also, if interested, I can post PIC code modifications for longer OFF sequences (15mins, 2 hours, etc). Remember, the ITPS can be re-programmed...

Hope this helps,
Andrei

Originally Posted by quinxy

The thing I don't get, and correct me if you've experienced something different, how can it be a shutdown controller if you have anything that requires 12 volts (like a 3.5" drive).

Here's what happens in my setup. I turn off the engine, the battery supplies 12.8 volts, the ITPS drops this to 10.2 for the power supply, and that 10.2 is passed to the 12 volt rail via the 120A PSU, meaning my hard drive suddenly stops functioning the instant I turn off the engine, the computer then because unusable/unstable and certainly can't shut down properly.

So, as a shutdown controller, it doesn't work at all for me, not even a tiny bit. If you use laptop harddrives then ok, you're probably fine, but it seems a pretty critical thing to not mention that this thing can't reliably or reasonably operate as a shutdown controller if you have anything that needs 12 volts, like a 3.5" drive.

I have heard of a couple of people using it with 3.5" drives, and I suppose those drives were just better able to handle serious undervoltages. Maybe other people are experiencing something different?

Quincy

Andrei,

From what I gather the ITPS when used in conjunction with the pw-70a only allows 60W through, rather than the 100W the psu is supposed to be able to supply. Is this still the case if the LDO is bypassed?

With the LDO bypassed, is there any risk to a M10000 mobo of an unregulated 12V (eg 13V-14V), also in terms of connecting the LCD to a HDD power connector, is this now unadvisable as the voltage will be too high? If so can you use the 'egg' that is on the cigar lighter connector? I am assuming that this 'egg' regulates the voltage from the cigar lighter?

Also, information about changing the off sequence would be handy!

Thank you

You are correct...

Thanks,
Andrei

Originally Posted by Laidback

When you say "Never use 3.5" drives" you mean "Never use 3.5" drives if you have a ITPS"?? 'Cause it doesn't work!

I'd like to see info on changing the off sequence as well. Do you need to use a high voltage PIC programmer to reprogram?

We use NeedHams programmers ($700/unit) but you can use other things as well. For example, the PICKit Flash Starter Kit ($39) does the job!

-Andrei

Originally Posted by bambooracer

I'd like to see info on changing the off sequence as well. Do you need to use a high voltage PIC programmer to reprogram?

The PW-70a can deliver 100Watts, but are you consuming 100Watts?
You can check your configuration by using the EPIA power simulator application available at http://www.mini-box.com, it is a pretty neat app that let's you play various power scenarios...

The M-10000 should have no problems at higher voltages on the 12V rail.

Unfortunately, I don't know anything about LCD stuff. The cigarettle lighter socket is NOT regulated.

Andrei

Originally Posted by lummox

Andrei,

From what I gather the ITPS when used in conjunction with the pw-70a only allows 60W through, rather than the 100W the psu is supposed to be able to supply. Is this still the case if the LDO is bypassed?

With the LDO bypassed, is there any risk to a M10000 mobo of an unregulated 12V (eg 13V-14V), also in terms of connecting the LCD to a HDD power connector, is this now unadvisable as the voltage will be too high? If so can you use the 'egg' that is on the cigar lighter connector? I am assuming that this 'egg' regulates the voltage from the cigar lighter?

Also, information about changing the off sequence would be handy!

Thank you