System Board 6495

MAXREFDES1006: 0.68V Power Supply Using MAX15112 as a Current-Mode Step-Down Regulator


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Input Type VIN (MIN)
(V)
VIN (MAX)
(V)
IOUT
(A)
Single/Multiple
Output
VOUT
(V)
POUT
(W)
Isolated/Non-Isolated Topology
DC 2.7 4.5 4 Single 0.68V 2.7W Non-Isolated Synchronous Buck

The MAX15112 high-efficiency, current-mode step-down regulator with integrated power switches operates from 2.7V to 5.5V and delivers up to 12A of output current in a small 2mm x 3mm package. The MAX15112 offers excellent efficiency with skip mode capability at light-load 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 MAX15112 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
MAXREFDES1006 Hardware Enlarge+


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A current-mode synchronous buck is demonstrated using the MAX15112 for a 0.68V DC output application. The power supply delivers up to 4A 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 MAX15112 current-mode controller. The power supply has been built and tested, details of which follow later in this document.

Design Resources

 
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MAX15112
High-Efficiency, 12A, Current-Mode Synchronous Step-Down Regulator with Integrated Switches

  • Continuous 12A Output Current
  • ±1% Feedback Accuracy Over Load, Line, and Temperature
  • Operates from 2.7V to 5.5V Supply