System Board 6483
MAXREFDES1003: 150mA, 4-Channel LED Driver in SEPIC Configuration Using MAX16813
|Input Type||VIN (MIN)
|DC||8||32||0.6||Single||19 to 24||14||Non-Isolated||Sepic|
The MAX16813 is a highly efficient, high-brightness (HB) LED driver that provides four integrated LED current-sink channels. An integrated current-mode switching controller drives a DC-DC converter that provides the necessary voltage to multiple strings of HB LEDs. The device accepts a wide 4.75V to 40V input voltage range and withstands direct automotive load-dump events. The wide input range allows powering HB LEDs for small- to medium-sized LCD displays in automotive and general lighting applications.
An internal current-mode switching DC-DC controller supports boost or single-ended primary inductor converter (SEPIC) topologies and operates in an adjustable frequency range between 200kHz and 2MHz. An integrated spread-spectrum mode helps reduce EMI. Current-mode control with programmable slope compensation provides fast response and simplifies loop compensation. An adaptive output-voltage control scheme minimizes power dissipation in the LED current-sink paths. The device has a separate p-channel drive (PGATE) pin that is used for output undervoltage protection. Whenever the output falls below the threshold, the external p-MOSFET is latched off, disconnecting the input source. Cycling the EN or the input supply is required to restart the converter.
The device consists of four identical linear current-sink channels, adjustable from 20mA to 150mA with an accuracy of ±3% using a single external resistor. Multiple channels can be connected in parallel to achieve higher current per LED string. The device also features a unique pulsed dimming control through a logic input (DIM), with minimum pulse width as low as 500ns. Protection features include output overvoltage, open-LED detection and protection, programmable shorted LED detection and protection, output undervoltage protection and detection, and overtemperature protection.
An LED driver in a SEPIC configuration using the MAX16813 is demonstrated for a 24V, 600mA output application. The device can drive up to 4 channels at once.
Designed, Built, Tested
This document describes the hardware shown in Figure 1. It provides a detailed systematic technical guide to designing an LED driver in a SEPIC configuration using Maxim’s MAX16813 LED driver. The LED circuit has been built and tested, details of which follow later in this document.
- 4-Channel Linear LED Current Sinks with Internal MOSFETs Independently Drive Multiple LED Strings
- Flexible Current-Mode Architecture Supports a Wide Range of Applications While Minimizing Interference
- Protection Features Enhance Fault Detection and System Reliability