Datasheet

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MSL2021 [DATASHEET]

42062A–LED–02/2013

1. Introduction

The MSL2021 LED driver for two-color systems includes a linear current controller for the main string, typically for white

LEDs, and a second floating buck controller for a color-adjust LED string. Both the switching and linear controllers drive

external MOSFETs to provide flexibility over a wide range of power levels (LED currents and voltages).

The MSL2021 adaptively manages the voltage powering the main LED string. A proprietary and patent pending

efficiency optimizer (EO) algorithm controls the voltage output of both AC/DC and DC/DC, isolated or non-isolated

topology, including ultra-low bandwidth single-stage PFC flyback controller.

The MSL2021 features peak current control and individual string PWM dimming, with the two strings driven at a 180

out

of phase. The main LED string’s current is ripple-free and has very high accuracy. The PWM dimming frequency for both

LEDs strings is 400Hz to give a predictable and wide dimming range. A thermistor connection allows automatic

compensation of luminous efficacy in a two-color LED fixture to maintain consistent color balance across temperature.

The MSL2021 operates from 9.5V to 15V input. The color-adjust string voltage regulation loop uses a constant off-time

control algorithm to achieve stable control with good transient behavior. For flexibility of design, off-time is set with an

external resistor. LED current in both the strings can be adjusted using internal 8-bit DACs.

The internal registers are I

C accessible. Integrated non-volatile EEPROM memory, also accessed through the I

C serial

interface, allows configuration at final test in case that the factory default settings need to be modified.

The MSL2021 is available in the space-saving 24-pin 4x4mm QFN package and operate over the extended -40°C to

105°C operating range.

2. Ordering Information

Note: 1. Lead-Free, Halogen-Free, RoHS Compliant Package

3. Application Circuit

Ordering code Description Package

(1)

MSL2021IN Two String LED Driver 4 x 4mm 24-pin QFN

SINGLE

STAGE

PFC

FLYBACK

CONTROLLER

FBO

C MAINS

WHITE LED STRING COLOR LED STRING

BRIDGE

RECTIFIER

EMI

FILTER

NTC

THM

DRV

MSL2021

LED

DRIVER

LINEAR

LED

DRIVER

MCU

FLOATING

BUCK LED

DRIVER

PWM1

VDD