MAXREFDES1233: 1.8V/10A Core Power Supply for CPUs, Microcontrollers, FPGAs, or DDR2 Interfaces Using the MAX20710

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Input Type VIN (MIN)
Isolated/Non-Isolated Topology
DC 11.4 12.6 10 Single 1.8 18 Non-Isolated Buck

The MAXREFDES1233 provides the internal core voltage (VCCINT) for CPUs, microcontrollers, FPGAs, or DDR2 interfaces. This reference design targets CPUs, microcontrollers, FPGAs, or DDR2 interfaces that require 1.8V for VCCINT from a 12V intermediary bus. The converter supports a maximum load of 10A at a 600kHz switching frequency. The MAXREFDES1233 is centered around the MAX20710 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 MAXREFDES1233.

The MAXREFDES1233 uses the MAX20710 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 MAX20710 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 MAX20710 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.

MAXREFDES1233 Board Enlarge+

Other features include the following:

  • PMBus Interface
  • Soft-Start
    • Protections
    • Output under/over-voltage alert
    • Current limit and short-circuit protection
    • Input UVLO at 3.9V
    • Over-temperature protection


PCB Layout

Test Results


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