System Board 6690

MAXREFDES1142: Ultra miniature Two Layer 4A, 1.8V Step-Down DC-DC Converter with Integrated Switches Using MAX15051

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Designed, Built, Tested

The Reference Design Document describes the hardware pictured below. It provides a detailed systematic technical guide to designing an ultra miniature Two Layer 4A, 1.8V Step-Down DC-DC Converter with Integrated Switches Using MAX15051. The hardware was built according to the linked Schematic, Bill of Materials and PCB Artwork. It was tested by Maxim’s expert applications engineering team in a state-of-the-art design lab and the Test Results are fully documented. Functionality of the design over all electrical operating conditions was verified with the MAXREFDES1142 Simulation Circuit using Maxim’s OASIS Circuit Simulation Tool. Downloadable ECAD/EDA files are available in 7 different formats including OrCAD, Altium, Mentor DX Designer, Eagle and more.


Input Type VIN (MIN)
Isolated/Non-Isolated Topology
DC 3 3.6 4 Single 1.8 7.2 Non-Isolated Synchronouse Buck

The MAX15051 is a high-efficiency switching regulator that delivers up to 4A load current at output voltages from 0.6V to (0.9 x VIN). The device operates from 2.9V to 5.5V, making it ideal for on-board point-of-load and postregulation applications. The total output-voltage accuracy is within ±1% over load, line, and temperature.

The MAX15051 features 1MHz fixed-frequency PWM operation, and pulse-skip mode to improve light-load efficiency. The high operating frequency allows for small-size external components. The low-resistance on-chip nMOS switches ensure high efficiency at heavy loads while minimizing critical parasitic inductances, making the layout a much simpler task with respect to discrete solutions.

The device incorporates a high-bandwidth (> 26MHz) voltage-error amplifier. The voltage-mode control architecture and the voltage-error amplifier permit a Type III compensation scheme to achieve maximum loop bandwidth, up to 200kHz. High loop bandwidth provides fast transient response, resulting in less required output capacitance and allowing for all-ceramic capacitor designs.

The output overload hiccup protection and peak current limit on both high-side and low-side MOSFETs provide for ultra-safe operation in the cases of short-circuit conditions, severe overloads, or in converters with bulk electrolytic capacitors.

The output voltage is adjustable by using two external resistors at the feedback or by applying an external reference voltage to the REFIN/SS input.

The MAX15051 offers a programmable soft-start time using one capacitor to reduce input inrush current. A built-in thermal shutdown protection ensures safe operation under all conditions. Other features include the following:

Key Features

  • 20μA Startup Current in UVLO
  • Programmable Input Undervoltage Lockout
  • Programmable Input Overvoltage Protection
  • Switching Frequency Synchronization
  • Adjustable Soft-Start
  • Programmable Slope Compensation
  • Fast Cycle-by-Cycle Peak Current Limit
  • 70ns Internal Leading-Edge Current-Sense Blanking
  • Hiccup Mode Output Short-Circuit Protection
MAXREFDES1142 Hardware Enlarge+

This board is not available for purchase.


Test Results

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Bill of Material

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Reference Design Document

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High-Efficiency, 4A, 1MHz, Step-Down Regulators with Integrated Switches in 2mm x 2mm Package

  • Internal 18mΩ RDS(ON) MOSFETs
  • Pulse-Skip Mode for High-Efficiency Light Load (MAX15050)
  • Continuous 4A Output Current