MAXREFDES1126: 0.72V/20A Supply for Xilinx® Ultrascale+ FPGAs


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Reference Guide


The MAXREDES1126 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 20A at a 400kHz switching frequency. The MAXREFDES1126 is centered around the MAX20743 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 MAXREFDES1126.

The MAXREFDES1126 uses the MAX20743 synchronous step-down regulator. The internal FETs 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 MAX20743 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 MAX20743 also offers protections such as input UVLO, output overvoltage/ undervoltage alerts, output overvoltage protection, over-temperature, 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, “PMBus Protocols for Controlling and Monitoring the MAX20743/MAX20730 Switching Regulators

Key Features

  • PMBus Interface
  • Soft-Start
  • Protections
    • Output under/over-voltage alert
    • Current limit and short-circuit protection
    • Over-temperature protection


Designed, Built, Tested

Board pictured here has been fully assembled and tested. Not available for sale.



Input Type Vin(Min) Vin(Max) Iout(Max) Single/Multiple Output Vout(V) Pout(W) Isolated/Non-Isolated Topology
DC 11.4 12.6 20 - 0.698 14.4 Non-Isolated Synchronous Buck


Input Type DC
Vin(Min) 11.4
Vin(Max) 12.6
Iout(Max) 20
Single/Multiple Output -
Vout(V) 0.698
Pout(W) 14.4
Isolated/Non-Isolated Non-Isolated
Topology Synchronous Buck

Maxim Devices (2)

Part Number Name Product Family Order Design kits and evaluation modules
MAX20743 Integrated, Step-Down Switching Regulator with PMBus Switching Regulators Buy Now Design Kits
MAX1615 High-Voltage, Low-Power Linear Regulators for Notebook Computers Linear Regulators (LDOs) Buy Now Not Available

Maxim Devices (2)

Part Number Product Family
Switching Regulators
Integrated, Step-Down Switching Regulator with PMBus
Linear Regulators (LDOs)
High-Voltage, Low-Power Linear Regulators for Notebook Computers
Not Available

Design Files (4)

Title Type Size Date
maxrefdes1126-schematic PDF 89KB 2019-02-04
maxrefdes1126-pcb PDF 2MB 2019-02-04
MAXREFDES1126 - Design Verification Testing PDF 276KB 2019-02-04
maxrefdes1126-bom PDF 76KB 2019-02-04
Date Type


(PDF, 89KB)



(PDF, 2MB)


MAXREFDES1126 - Design Verification Testing

(PDF, 276KB)



(PDF, 76KB)

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