Electronic Design

FPGA Power Management

Sponsored by: NATIONAL SEMICONDUCTOR

What is an FPGA?

A field-programmable gate array (FPGA) is an IC that can include thousands of identical, programmable logic cells. A matrix of wires and programmable switches interconnects individual logic cells. A typical design involves specifying the simple logic function for each cell and selectively closing the switches in the interconnect matrix. FPGAs are primarily used to prototype an IC-based system. When the design is finalized, designers can convert the logic into hardwired ICs that operate at higher speeds. To operate properly, the FPGA must employ appropriate power-management technology.

What are the powering requirements for an FPGA?

PGA power depends on the requirements of internal circuits. The FPGA has three major configurable elements: configurable logic blocks (CLBs), I/O blocks (IOBs), and interconnects. The CLBs provide the functional logic elements. The IOBs provide the interface between the package pins and internal signal lines. The programmable interconnect resources provide routing paths to connect the inputs and outputs of the CLBs and IOBs onto the appropriate networks. The voltage applied to the CLBs (or core) is designated VCCINT. VCCO is the voltage supplied for IOBs. Some FPGAs have an additional voltage input designated as VCCAUX.

What are typical voltage and current values for VCCINT?

Typical voltages are 1.2, 1.5, 1.8, 2.5, and 3 V, with currents up to 12 A. The larger the number of CLBs, the lower the voltage and higher the current. In addition, VCCINT should rise monotonically, with no dip allowed.

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TAGS: Digital ICs
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