MAXREFDES1269: 5V/20A, Synchronous Step-Down Converter Using the MAX20098

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Input Type VIN (MIN)
Isolated/Non-Isolated Topology
DC 6 36 20 Single 5 100 Non-Isolated Synchronous Buck

The MAXREFDES1269 demonstrates how to build a DC-DC buck converter using the MAX20098 step-down controller for 5V DC output applications from a 6V to 36V input. This reference design delivers up to 20A at 5V output. The design uses a six-layer board. Table above shows an overview of the design specification.

The MAX20098 is a 3.5V to 36V synchronous, step-down DC-DC controller. It uses a current-mode control architecture and can operate in the pulse-width modulation (PWM) or skip-mode control schemes. The device can operate in dropout conditions at a 99% duty cycle. The external sync pin (FSYNC) logic input, under light-load applications, allows the device to operate either in the skip-mode or fixed-frequency forced-PWM (FPWM) mode to minimize electromagnetic interference (EMI). The output voltage is programmable from 1V to 10V with fixed 3.3V/5V options. The feedback (FB) regulation is accurate within ±1% over -40°C to +125°C.

Key Features

  • Efficiency = 88% at Full Load
  • Output-Voltage Ripple < 50mV across Line and Load Conditions
  • Overshoot < 150mV for 50% Load Step
  • Continuous Conduction Mode (CCM) Operation
  • Internal Soft-Start
  • Overall Solution Size = 572mm2
MAXREFDES1269 Board Enlarge+

Designed, Built, Tested

The reference design provides a detailed, systematic technical guide to design a buck converter using the MAX20098 for high voltage and smaller size. The hardware is shown in the photo above. The small board shows the actual solution size. Refer to the MAX20098 and MAX20098EVKIT data sheets for device operation details. The power supply was built and tested. The details of which are available in the Design Resources documents.


PCB Layout

Test Results


Versatile Automotive 36V 2.2MHz Buck Controller with 3.5µA IQ

  • Meets Stringent OEM Module Power Consumption and Performance Specifications
  • Enables Crank-Ready Designs
  • EMI Reduction Features Reduce Interference with Sensitive Radio Bands without Sacrificing Wide Input Voltage Range