AN 721: Creating an FPGA Power Tree

ID 683564
Date 6/30/2019

Power Tree Input Supply Voltage

Determine the input supply voltage before creating an FPGA power tree. Systems typically favor one of two implementations: a 12V input source, or a low voltage (5V or 3.3V) input source.

Most FPGA inputs require a voltage of ≤3.3V. Building an FPGA power tree from a low voltage input source often allows for a smaller, more efficient system. If you use an input source of 12V or higher, or if the Early Power Estimator (EPE) spreadsheet estimates the total FPGA current consumption is very high, Intel recommends that you use a two-stage voltage solution, where:

  • A first-stage power converter converts a high voltage to a lower intermediate voltage, and
  • A second-stage power converter converts the intermediate voltage to the final FPGA input voltages
Figure 1. Two-Stage FPGA Power TreeThis two-stage FPGA power tree voltage solution allows you to power the FPGA inputs with efficient, low-voltage converters. The figure shows a 12V power converter converting the input supply to a lower 5V or 3.3V intermediate voltage. The point of load (POL) low-voltage converter then converts the intermediate voltage to the final FPGA input voltages, usually between 0.85V and 3.3V.

You must determine the input supply voltage and voltage architecture before you select power converters.