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.
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.