Spartan-6 FPGA Power Management
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UG394 (v1.1) September 4, 2012
Chapter 5
Power Estimation
Introduction
Xilinx provides a complete power estimation solution using power estimators and
analyzers, power-driven implementation tool algorithms, and a variety of power-related
documentation. The Power Advantage page provides access to these tools,
documentation, and news:
http://www.xilinx.com/products/technology/power/index.htm
To estimate the total power consumption (quiescent plus dynamic) for a specific design use
one of the following tools:
•
The XPower Power Estimator spreadsheet provides quick, approximate estimates,
and does not require the design’s netlist.
•
The XPower Analyzer is delivered with the ISE Design Suite software and uses a
netlist as input to provide more accurate estimates.
The XPower Power Estimator (XPE) spreadsheet is a power estimation tool typically used
in the pre-design and pre-implementation phases of a project. XPE assists with architecture
evaluation and device selection, and helps in selecting the appropriate power supply and
thermal management components. For comparison and analysis, the XPE spreadsheet for
the Spartan-6 family also includes the Extended Spartan-3A family.
XPE considers the resource usage, toggle rates, I/O loading, and many other design
factors. Combined with device models, the estimated power distribution can be calculated
in XPE. The device models are extracted from measurements, simulation, and/or
extrapolation.
After implementation, the XPower Analyzer (XPA) tool (available in the ISE Design Suite
software) is used for more accurate estimates and power analysis. For more information
about XPA, see the XPower Analyzer Help.
Voltage Regulators
The choice of a voltage regulator depends on system requirements and the estimated
power consumption requirements for the FPGA. Use the XPower tools to calculate the
requirements for a specific device and design. Then choose a regulator from a
pin-compatible family so the current capability can be adjusted up or down. External
power FETs are easy to upgrade. A soft-start feature that controls output ramp time is
useful.
With care, use of overcurrent protection is possible, such as foldback or fuses. Be aware
that capacitors are charging at power-on and might draw a significant amount of current
for a short time.