MAXREFDES1131

Description

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.

Features & Benefits

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