Calculating power, The clock control, Calculating power –31 – Altera Stratix IV GT 100G User Manual
Page 53: The clock control –31
Chapter 6: Board Test System
6–31
The Clock Control
October 2010
Altera Corporation
Stratix IV GT 100G Development Kit User Guide
Calculating Power
The Power Monitor calculates power by measuring two different voltages with the
LT2418 A/D and applying the equation P = V × I to determine the power
consumption. The LT2418 measures the voltage after the appropriate sense resistor
(Vsense) and the voltage drop across that sense resistor (Vdif). The current (I) is
calculated by dividing the measured voltage drop across the resistor by the value of
the sense resistor (I = Vdif/R). Through substitution, the equation for calculating
power becomes P = V × I = Vsense × (Vdif/R) = (Vsense) × (Vdif) × (1/.003).
You can verify the power numbers shown in the Power Monitor with a digital
multimeter that is capable of measuring microvolts to ensure you have enough
significant digits for an accurate calculation. Measure the voltage on one side of the
resistor (the side opposite the power source) and then measure the voltage on the
other side. The first measurement is Vsense and the difference between the two
measurements is Vdif. Plug the values into the equation to determine the power
consumption.
The Clock Control
The Clock Control application sets the Si5338 programmable oscillator to any
frequency between 0.16 MHz and 710 MHz. Each clock generator device contains a
PLL and buffer inside its device that drives four independent LVDS clocks to the
FPGA core for the DDR3 and four clocks to the QDRII memory interfaces. There is
also a clock generator that drives four independent LVDS clocks to the reference clock
inputs for the transceivers. All of these clock generators come pre-programmed with
the 100G development board. The memory clocks are pre-programmed to 100 MHz
and the transceiver clocks are pre-programmed to 706.25 MHz.
The Clock Control application runs as a stand-alone application. ClockControl.exe
resides in the
<install dir>\kits\stratixIVGT_4sgt100g5_100g\examples\board_test_system
directory. On Windows, click Start > All Programs > Altera > Stratix IV GT 100G
Development Kit
<version> > Clock Control to start the application.
f
For more information about the Si5338 and the Stratix IV GT 100G development
board’s clocking circuitry and clock input pins, refer to the
.