Choosing the right power supply for your FPGA

Field-programmable gate arrays and complex programmable logic devices require from 3 to 15, or even more, voltage rails. The logic fabric is usually at the latest process technology node that determines the core supply voltage. Configuration, housekeeping circuitry, various I/Os, SerDes transceivers, clock managers, and other functions all have differing requirements for voltage rails, sequencing/tracking, and voltage ripple limits. An engineer must consider all of these issues when designing a power supply for an FPGA.

As programmable logic devices and FPGAs assume the role of a system on a chip on your board, powering these devices is comparable to powering an entire system. High-end FPGAs such as the Xilinx Virtex M series and the Altera Stratix series easily have ten to15 unique rails. Lower-density FPGAs such as the Xilinx Kintex and Spartan series, or the Altera Arria and Cyclone series, can have between two to10 rails depending on the application.

With FPGAs varying so greatly, it is critical that you choose the right power supply for each application. You must define the set of power regulators for the overall power level of each rail, the rails’ sequencing requirements, and system power-management needs. Moreover, as process technology nodes become smaller in FPGAs, tighter tolerances are needed on the voltage-supply rails. This is why regulators with 1% regulation accuracy across line/load and PVT variations are so critical.

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If this abstract has piqued your interest, read the full article online in the August issue of Electronic Specifier Design, by clicking here.