System Board 6882

MAXREFDES1131: 0.72V/12A Supply for Xilinx Ultrascale+ FPGAs

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Input Type VIN (MIN)
Isolated/Non-Isolated Topology
DC 11.4 12.6 12 Single 0.72 8.64 Non-Isolated Synchronous Buck

The MAXREFDES1131 provides the internal core voltage (VCCINT) for Xilinx Ultrascale+ FPGAs. This reference design targets FPGAs with a -2L speed grade that require 0.72V for VCCINT from a 12V intermediary bus. The converter supports a maximum load of 12A at a 400kHz switching frequency. The MAXREFDES1131 is centered around the MAX20730 step-down regulator, which is configured for standalone operation. However, the PMBus interface allows for monitoring and control of various converter parameters. All circuitry for the PMBus interface is provided and the MAXPOWERTOOL002# can be used to communicate with the MAXREFDES1131.

The MAXREFDES1131 uses the MAX20730 synchronous step-down regulator. The internal MOSFETs and control loop compensation allow for a compact design with minimal external resources. Additionally, the differential sense lines allow for accurate sensing of the CPU core voltage when located remotely from the MAX20730 IC. The loop gain is selectable to allow design flexibility between stability and output capacitance. A programmable soft-start limits inrush currents during startup. The MAX20730 also offers protections such as input UVLO, output overvoltage/ undervoltage alerts, output overvoltage protection, overtemperature, and current limiting. Moreover, the PMBus interface allows additional parameters to be monitored such as input voltage, output voltage, output current, and temperature. For a full list of PMBus commands, see Application Note 6042.

Key Features

  • PMBus Interface
  • Soft-Start
  • Protections
    • Output Undervoltage/Overvoltage Alert
    • Current Limit and Short-Circuit Protection
    • Overtemperature Protection
MAXREFDES1131 Board Enlarge+

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Designed, Built, Tested

The power supply has been built and tested. This document describes the design of the hardware shown above.

Design Resources


Integrated, Step-Down Switching Regulator with PMBus

  • High Power Density and Low Component Count
  • Optimized Component Performance and Efficiency with Reduced Design-In Time
  • Increased Power-Supply Reliability with System and IC Self-Protection Features

High-Voltage, Low-Power Linear Regulators for Notebook Computers

  • 4V to 28V Input Range
  • 8µA (max) Quiescent Supply Current
  • <1µA Shutdown Supply Current