System Board 6496

MAXREFDES1020: 0.68V Power Supply Using MAX15118 as a Current-Mode Step-Down Regulator

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Input Type VIN (MIN)
Isolated/Non-Isolated Topology
DC 2.7 4.5 6 Single 0.68 4 Non-Isolated Synchronous Buck

The MAX15118 high-efficiency, current-mode step-down regulator with integrated power switches operates from 2.7V to 5.5V and delivers up to 18A output current in a small 2mm x 3mm package. The MAX15118 offers excellent efficiency with skip mode capability at lightload conditions, yet provides unmatched efficiency under heavy load conditions. The combination of small size and high efficiency makes this device suitable for both portable and nonportable applications.

The MAX15118 uses a current-mode control architecture with a high-gain transconductance error amplifier, which allows a simple compensation scheme and enables a cycle-by-cycle current limit with fast response to line and load transients. A factory-trimmed switching frequency of 1MHz (PWM operation) allows for a compact, all-ceramic capacitor design.

Integrated switches with low on-resistance ensure high efficiency at heavy loads while minimizing critical inductances.

Key Features

  • ±1% Feedback Accuracy Over Load, Line, and Temperature
  • Input Undervoltage Lockout
  • Programmable Soft-Start
  • Adjustable Soft-Start
  • External Reference Input
  • Selectable Skip Mode Option for Improved Efficiency at Light Loads
MAXREFDES1020 Board Enlarge+

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A current-mode synchronous buck is demonstrated using the MAX15118 for a 0.68V DC output application. The power supply delivers up to 6A at 0.68V

Designed, Built, Tested

This document describes the hardware shown in Figure 1. It provides a detailed systematic technical guide to designing a synchronous buck using Maxim’s MAX15118 current-mode controller. The power supply has been built and tested, details of which follow later in this document.

Design Resources


High-Efficiency, 18A, Current-Mode Synchronous Step-Down Regulator with Integrated Switches

  • Continuous 18A Output Current
  • ±1% Feedback Accuracy Over Load, Line, and Temperature
  • Operates from 2.7V to 5.5V Supply