System Board 6893

MAXREFDES1080: 5V/1A LED Driver in Step-Down, Constant-Current Configuration Using MAX16820

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As LEDs are becoming more and more popular, so is the need for small, cost-effective solutions. The MAXREFDES1080 is a constant-current, high-brightness LED (HB LED) driver. It delivers 5W of power to a single LED string, which is included in the design. The circuit is in a step-down configuration and is designed for a 12V input.

The design uses the MAX16820 controller. This device minimizes the number of external components while delivering constant current over a wide input range. The MAX16820 can operate from a 4.5V to 28V input voltage range and features a 5V/10mA on-board regulator. A hysteretic control algorithm ensures excellent input-supply rejection and fast response during load transients and PWM dimming. These devices operate up to 2MHz switching frequency, thus allowing for small component size.

The MAXREFDES1080 delivers power efficiently with a compact solution and low component count. In the current semiconductor industry, where size and component count are becoming more and more important, this circuit effectively delivers the required power for HB LEDs and is perfect for architectural and ambient lighting.

Key Features

  • 5W Output Power
  • High-Side Current Sense
  • Adjustable Constant LED Current
  • ±5% LED Current Accuracy
  • Wide Dimming Range (5000:1)
  • Dedicated Dimming-Control Input
  • 20kHz Maximum Dimming Frequency
  • Hysteretic Control: No Compensation
  • Up to 2MHz Switching Frequency
  • 5V, 10mA On-Board Regulator
MAXREFDES1080 Board Enlarge+

This board is not available for purchase.

Designed, Built, Tested

This document describes the hardware shown above. It provides a detailed, systematic technical guide to designing a step-down, constant current LED driver using the MAX16820 controller. The LED driver design has been built and tested, details of which follow later in this document.

Design Resources


2MHz High-Brightness LED Drivers with High-Side Current Sense and 5000:1 Dimming

  • Simple High-Power LED Lighting Design with Accurate LED Current Control
  • Wide Dimming Range (5000:1)
  • Minimizes Number of Components to Save Space and Cost