Manualshelf

User guide

ManualsBrandsAltera ManualsAutomotiveCyclone III FPGA
31323334353637383940
Chapter 7: Power Measurement 7–5
Changing the Design Example
September 2010 Altera Corporation Cyclone III FPGA Development Kit User Guide
Calculating Power
To obtain the power P in watts, measure the voltage across the sense resistors, V
SENSE
,
and calculate the nominal power as follows:
If
V
SENSE
= Voltage measured across the sense resistor
I
SENSE
= Current through the sense resistor
V
SUPPLY
= FPGA supply voltage
R
SENSE
= Sense resistor value in Table 7–5.
then
where
V
SUPPLY
is 1.2 V for the FPGA core and 2.5 V for FPGA I/O.
Voltage measurements on the DMM should increase as frequency and resource
utilization increases according to Table 7–2 and Table 7–3 on page 7–2.
Changing the Design Example
The development kit includes source code for the Cyclone III power design example
so you can use it as a starting point for your own measurements.
The design example uses 19 stamp.v modules, each with 8 outputs, for a total of
152 output pins. It assigns the pins selected as outputs to the HSMC connectors J8 and
J9.
To change the number of outputs, modify the design example and assign the pins
appropriately.
1 Power should track linearly with frequency and percentage resources. If you observe
superlinear power measurements, some temperature issue may be the cause.
Equation 7–1.