Thread: Has anyone gotten a sproggy to work with EPIA boards?

So, 2 amps is more a realistic draw on the 12 volt input right?

by 12v input, do you mean the front side connection from the car battery to the sproggy?

I am not sure how to calculate the input amp requirements.

I have a sproggy 2.7, which has the following specs: (approx 85watts)

3.3 5A (peak 6.5)
5 10A (peak 13)

You don't have 10A on a the 5V line...(5A max 6.5A)

You have only one max for the +5V....

Are you using low ESR cap?
Put a bigger output ESR CAP on the 5V output (~1000 uf)

No, actually I have version 2.7 of the sproggy. It has an extra 787 for twice the 5v power output. (2 * 5A = 10A and 2*6.5=13A peak)

I bought an ATX extender cable and then cut it in half so I could put a meter in-line to measure the amount of current used on each rail.


Epia M9000
512MB PC2700 RAM
Microsoft Intellimouse Optical
Microsoft Elite Keyboard
Ethernet attached

(also attached during these tests, but not part of these current measurements):
IBM Travelstar 5400 40GB laptop HD
AOpen Slot load DVD

Measurements were made by placing a Fluke 189 digital meter in-line betwen a 250W ATX power supply and the motherboard. The meter was placed in "Fast-Max and hold" mode to measure peak instantaneous current usage.

The results:

12v:
Powerup: 185 mA
Max (playing DVD) 219 mA

5v:
Powerup: 2.939 A
Xp loading: 3.366 A
Playing DVD: 3.48 A
Max: 3.965 A

3.3v:
This is where it gets a little more interesting.
Tying all 3.3v ATX lines together with the meter in-line prevents the motherboard from posting. There is a peak 7.673A on initial powerup, but no POST. I verified the motherboard could post with all lines tied together, but with no meter inline.

Next I tried only measuring ATX pin 1 & 2 (3.3v) together, while keeping pin 11 (3.3 + 3.3 v sense) separate

The motherboard posts in this configuration and measurements are:

pin 1 & 2: startup: 1.85A
pin 11 : startup: 1.27A
-------------------------------------------
3.12A

Now, adding these up doesn't equal the 7.673A I saw in the failure case (with all 3 lines tied together). I am not really sure what this means. My electronics theory is pretty marginal. I don't know if this is just an artifact of the measurement process. Maybe while measuring one set of pins, more power is being sent down the others path since it has less resistance?

My only conclusion is that it must need upwards up 8A peak on startup. ??

I also measured the 5v standby line to see how much power is used while the computer is under standby mode:
176 mA while the computer is on
297 mA while windows is in standby mode

note: with the computer is plugged into an ethernet hub, power usage in standby drops by 30mA, apparently stealing a little power from the hub?

So for a 24 hour period you would need 7.2 A-hours of battery life. I suspect this might be much less with slower RAM, and less than 512MB! In any case, it was quite cool to put the computer into standby while streaming music over the internet, then resume a minute later and have the music instantly startup where it left off and continue streaming. nice.

Alright, after measuring the M9000 power requirements and finding the possible extreme requirements for the 3.3v rail, it was time to build something new to try.

Tonight I worked up a Sproggy 2.7x

The 2.7x is has two Max 787's and two Max 788's.

This should provide the following power output:

3.3V: 10A (13A peak)
5V: 10A (13A peak)
12V: 1.3A

Luckily I had lots of extra sproggy components, so I had everything necessary to double the 3.3V output current.

Okay, now the bad news. I built it, powered it up, and same result. Motherboard fan powers up, but it never POSTs.

Since I don't have the 2.8, I don't have the ATX power-on signal integrated. This worries me that the motherboard is not expecting power, or is not providing the correct behaviour on ths PS-ON pin.

Not sure what else to try at this point.

I modified my 2.7x today and added 5v standby and a transistor to support the PS-ON pin 14 ATX signal.

After initially applying power (i.e. only 5v stdby), I see the network light on the motherboard establish connection with my ethernet switch, so 5v standby power is good.

Next I short pins 6 and 8 on the motherboard to power things up. The sproggy powers up just fine in response to this action.

No go though. same old story. processor fan spins up, but no POST.

????

More experimenting...

Using a known good desktop ATX power supply hooked up to the M9000...

The Power good line seems to be unncessary. Everything powers up just fine with this line "cut"

Next I tried removing the PS_ON line and starting the power supply by shorting to ground. (i.e. the motherboard is not connected to the power supply's PS_ON). The results are very interesting. The power supply starts and provides the necessary voltages. The M9000 fan starts but does not POST. Exact same behaviour as the sproggy! Could be a coincidence, but this reinforces my original theory that its not a lack of power (especially since I have modified my 3.3 rail) but rather a signalling problem with powergood or PS_ON.

Many thanks for all your work...

I have a M9000 and I'am building my dc-dc supply now with a "new" design...

Basicly I use a PIC for the shutdown ctrl and the PG, PS_ON...

Removed all the negative voltage...

Your thread is very very helpfull...

I'll have a problem with my 3.3V

3.3V @ 7.673A on startup that's hudge....

On Via Spec:
Playing DVD
+3.3V 3.37V 3.38A 11.3906W

Perhaps a big caps on the 3.3V will be enough for the startup...

Hope you'll find the bug with powergood or PS_ON signal!

If I find something I'll let you know...

What is the specification for the PS_ON signal? Did you check it?

PS_ON# is an active low signal that turns on all of the main power rails including 3.3VDC, 5VDC,
-5VDC, 12VDC, and -12VDC power rails. When this signal is held high by the PC board or left open
circuited, outputs of the power rails should not deliver current and should be held at a zero potential with
respect to ground. Power should be delivered to the rails only if the PS_ON# signal is held at ground
potential. This signal should be held at +5VDC by a pullup resistor internal to the power supply.