Zedboard Power with Current Sense

Hello,
did anybody try to estimate the power consumption of the Zedboard using the onboad current sense J21?
If I but my Osciloscope on the those pins I'm measuring 3.2mV?
But how does that relate to the power drawn?
P=U^2/R -> With the resitance beeing 10mOhm?
Using this would result in a power consumption below mW which seems unrealistic.
Cheers
eactor

I also checkt if the board is sneaking power elsewhere USB, PowerOverEthernet ... but without luck

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0 bhfletcher over 12 years ago

ZedBoard doesn't have multiple power sources, so the measurement across J21 should be accurate. The resistance in R292 is 10m-OHM, although the correct part number to use is Stackpole CSR1206FK10L0. This is a 1%, 0.5W, 1206 SMD resistor.

http://www.seielect.com/Catalog/SEI-CSR_CSRN.pdf

Based on your measurement of 3.2 mV across a 10m-ohm resistor, you can measure the current as I = V/R = 320mA. Since the input voltage source is 12V, you can calculate the power input to the board as P = I*V (V=12V, not the V you measured). So...

P = 320mA * 12V = 3.84 W

Are you running the default, out-of-box design that ships with ZedBoard?

Bryan
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0 bhfletcher over 12 years ago

ZedBoard doesn't have multiple power sources, so the measurement across J21 should be accurate. The resistance in R292 is 10m-OHM, although the correct part number to use is Stackpole CSR1206FK10L0. This is a 1%, 0.5W, 1206 SMD resistor.

http://www.seielect.com/Catalog/SEI-CSR_CSRN.pdf

Based on your measurement of 3.2 mV across a 10m-ohm resistor, you can measure the current as I = V/R = 320mA. Since the input voltage source is 12V, you can calculate the power input to the board as P = I*V (V=12V, not the V you measured). So...

P = 320mA * 12V = 3.84 W

Are you running the default, out-of-box design that ships with ZedBoard?

Bryan
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