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If I have a PCM-9361 Intel Atom board that says it uses 12V power supply and under max power consumption it uses 0.09A - does this mean the board uses 1.08 watts per hour?

Also, the board specs says if being powered by 5V, the max current is 2.38A... why does 5V use a lot more current than 12V?

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    \$\begingroup\$ You need to work on your understanding of units. A (Ampere) is the unit of current, W (Watt) is the unit of power, and watts per hour doesn't make sense. \$\endgroup\$
    – starblue
    Commented Mar 13, 2011 at 8:52
  • \$\begingroup\$ "The output of the power plant increased by 1000 W per hour." \$\endgroup\$
    – endolith
    Commented Mar 13, 2011 at 23:08
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    \$\begingroup\$ @starblue - "watts per hour" indicates the rate of change in power, what's wrong with that? ;-) \$\endgroup\$
    – stevenvh
    Commented Jun 23, 2012 at 14:45
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    \$\begingroup\$ @endolith: But that's not what he is talking about. You wouldn't say something "uses" some number of W/h. -1 for sloppy units. \$\endgroup\$ Commented Jun 23, 2012 at 14:53
  • \$\begingroup\$ @OlinLathrop: He said "watts per hour" doesn't make sense. I pointed out that it does, just not in this context. \$\endgroup\$
    – endolith
    Commented Jun 23, 2012 at 18:15

2 Answers 2

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watts are already joules per second. "watts per hour" is wrong.

If it draws 0.09A max, then it uses 1.08 watts max. Max doesn't necessarily mean average, though.

I don't know why it would draw 10x as much power at lower voltage. What kind of board is this?

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  • \$\begingroup\$ Thanks for the reply. The board is an embedded single board computer. The datasheet for the board is here: support.advantech.com.tw/support/… \$\endgroup\$
    – user3367
    Commented Mar 13, 2011 at 1:39
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    \$\begingroup\$ It looks like the board uses both 5V and 12V at the same time. The board uses 2.38 A at 5V to power the board, and .09 A at 12V to power an LCD or optional add-on card. \$\endgroup\$
    – Ryan
    Commented Mar 13, 2011 at 3:27
  • \$\begingroup\$ @Ryan, you should make an answer with explanation and links, that is what I expected the case to be also. \$\endgroup\$
    – Kortuk
    Commented Mar 13, 2011 at 10:14
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The board is primarily powered from the 5V supply, so that uses most of the power. The 5V supply is required for the board to work.

The 12V seems just to be needed for some optional stuff, so it is not strictly required ("12V is optional for LCD inverter and add on card").

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