ITPS Regulation

**NewTechFool** · 01-25-2004, 01:17 PM

This week I got a fancy new power supply (HP 6542A), so I decided to do some testing on the ITPS from ituner.com (http://store.ituner.com/ituner/itps.html). There have been a lot of discussions around this regulator/shutdown controller, but I have not seen any extended measurements of the device.

I tested it with no load and with low and high load. For load I used a standard 9003 automotive light bulb. Low load was both low and high beams connected in series which is about 3 amps at 12 volt (36 watts), and high load was only high beams which is about 5 amps at 12 volts (60 watts). I did not want to destroy my PC testing the voltage.

Attached you can see a graph of the results.

For reference my Epia 1000M consumes between 3.3 and 4.6 amps depending on the task in a CASETRONIC 2699R case with DC-DC power supply, 5400rpm HD, Wireless USB (from Microsoft) and no CD.

As you can see from the graph the ITPS crank survival without a tank circuit is not going to happen without divine intervention. I have not been able to find any voltage range of the DC-DC power supply in the 2699R case, but if we assume 12 volts plus minus 10 percent, that should give us a range.

We can see that we reach the critical voltage at about 13.1 volts at low load, but if you load up your PC with peripherals and power your LCD off it also and have the high load you need about 13.7 volts. If you take the 12.65 volt float voltage of a fully charged typical deep cycle battery that you might use in a tank circuit as a secondary battery, then you can see that you even need the motor running in order to use your PC safely.

Something to think about.

**none** · 01-25-2004, 03:14 PM

Good work. One thing to keep in mind is that the ITPS works wonderfully as a shutdown controller ONLY, bypassing the regulation. It is the most complete standalone shutdown controller available when used in this way.

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

**MikeH** · 01-25-2004, 07:17 PM

NewTech,

Great work!

I have not been able to find any voltage range of the DC-DC power supply in the 2699R case, but if we assume 12 volts plus minus 10 percent, that should give us a range

Looking at a picture of the PSU in the 2699R, it appears to be the same (or a slight modification of) the standard Casetronic or Morex PSU . The Casetronic web page FAQ says the input 12v tolerance is +/-5% (not 10%). This makes the ITPS regulator look ever worse!

Thanks for the info.

**Ricky327** · 01-25-2004, 10:00 PM

Good post NewTechFool.

I wonder if they ever look at this kind of testing. Even a zero dropout linear regulator can cause problems.

They even recommend adding a battery based tank with a diode...what are they thinking

**parawing742** · 01-25-2004, 11:19 PM

My ITPS works fine running a Morex 60W power supply even with the engine off. A extra battery isn't nessessary for everyone.

**shakes** · 01-25-2004, 11:54 PM

Originally Posted by parawing742

My ITPS works fine running a Morex 60W power supply even with the engine off. A extra battery isn't nessessary for everyone.

but does it survive a crank? i think he was just saying you need the extra battery to survive the crank.

also... do you have all laptop components? i suspect people with 12v drives will have issues running with the car off.

**parawing742** · 01-26-2004, 12:06 AM

Originally Posted by shakes

but does it survive a crank? i think he was just saying you need the extra battery to survive the crank.

also... do you have all laptop components? i suspect people with 12v drives will have issues running with the car off.

No, it will reboot upon starting the engine. I use a 7200RPM desktop hard drive.

**adamis** · 01-26-2004, 12:08 AM

I can't believe some of you guys still don't understand the ITPS. It is DESIGNED for an automotive application. Maybe it isn't right for your application for some reason but I have a feeling that most of the people who use the ITPS don't have many complaints with it's use in an automotive environment.

The ITPS when used with the PW-70 powersupply and an Epia M motherboard will not drop out if the voltage drops below 12 volts. I've had this thing down to 10.5 volts and it didn't drop out. I can run my system for a long time without the motor running to boot. Of course you do have to stick with the components the ITPS is designed for...

Keep in mind that the Epia motherboards don't use 12v (unless someone else can prove me wrong and I'm talking about just the board, not serial devices for the sake of keeping it simple). In this case the PW-70 doesn't need the 12 volts to safely get the 5 volts and 3.3 volts to power the motherboard. Also stick to laptop harddrives because they run off of the 5 volt rail and are better suited to rougher environments.

As for crank survivability no it won't survive a crank but it isn't advertised as being able to do such a thing. That is what the small battery is for.

**shakes** · 01-26-2004, 12:18 AM

adamis ...

you are correct in what you say ... how the PC can run jsut fine using the ITPS with less than 12v with laptop components. it's all the guys with 12v components that have issues.

but it's not that people don't understand the ITPS ... it's simply that the ITPS has limitations and people are pointing those limitations out. If someone is planning on putting 12v components in their system they need to be aware of the issues they may face with the ITPS.

likewise ... no one ever said it would or should survive a crank .. nor has anyone said it's a poor product ... again we're just pointing out the fact that with the ITPS/PW-series setup you'll need an SLA or some form of tank. just trying to keep people from buying into something without understanding the limitations.

from what I hear the opus does survive a crank ... and it's a better supply in that you can make use of all 100w+ regulated (the ITPS limits you to 60w regulated) ... the opus, of course, has it's downfalls as well.

however the ITPS/PW combo will save you about $60 so it's a much better solution for some (myself included) despite it's limitations.

and as you've said, these limitations aren't a problem if you have the right components in your system.

just be careful ... cause a lot of these guys DO understand the ITPS and are just looking out for those who don't.

**adamis** · 01-26-2004, 06:43 AM

Alright, in that respect I understand and I agree the facts should be represented so others know what they are getting into before they buy it. I would like to add however that if you don't own or have used an ITPS before then you should be cautious in making statements regarding the product.

I also want to correct the statement that you need your car running in order for the ITPS to run. The facts are (and if the guy tested it, I'm not sure why he made the statement) I have had the voltage down to almost 10.5 volts while running my computer and didn't have a problem, and I can't be the only person. People need to know that his statement is inconsistent with other people's experience. Maybe it cut out on him but this could be as simple as a bad wiring job or dirty terminals.