TI(NS)LM3549高效大功率RGBLED驱动方案

TI(NS )公司的LM3549是输出电流高达700mA的高效大功率RGB LED驱动器,它有三个恒流LED驱动器和一个降压升压开关电源(SMPS),用来高效地驱动RGB LED.LM3459具有过流和超温保护,I2C兼容接口以及欠压锁住, 降压升压转换器的峰值效率95%,主要用在手持视频投映仪和大功率LED驱动.本文介绍了LM3549主要特性和指标,方块图,典型应用电路以及评估板电路图和材料清单.

The LM3549 is a high power LED driver with up to 700mA output current. It has three constant current LED drivers and a buck boost SMPS for driving RGB LEDs with high efficiency.

LED drivers are designed for sequential drive so only one driver can be enabled at a time.

LED driver output current settings can be stored to integrated non-volatile memory which allows stand-alone operation without I2C interface. Non-volatile memory is rewritable so current setting can be changed if needed.

LM3549 has a fault detection feature that can detect several different fault conditions. In case of a fault error flags are set and FAULT output sends interrupt to control logic. Error flags can be read through I2C interface.

Total brightness can be controlled with PWM input or with master fader register if I2C interface is used.

LM3549主要指标:

■ Integrated buck-boost converter

■ Programmable LED drivers

■ 700 mA maximum drive current

■ ±6% Current accuracy over temperature

■ 24-pin LLP package

LM3549主要特性:

■ Over-current protection

■ Over-temperature protection

■ I2C compatible interface

■ Under-voltage lockout

■ LED open and short protection and detection

■ 95% peak efficiency buck-boost converter

■ NVM memory for calibration data and standalone usage without I2C control

■ Soft start

LM3549应用:

■ Portable video projectors

■ High power LED driving

图1. LM3549方框图

图2. LM3549典型应用电路图

LM3549评估板

The LM3549 is a high power LED driver with up to 700mA output current. It has three constant current LED drivers and a buck boost SMPS for driving RGB LEDs with high efficiency.

LED drivers are designed for sequential drive so only one driver can be enabled at a time.LED driver output current settings can be stored to integrated non-volatile memory which allows stand-alone operation without I2C interface. Non-volatile memory is rewritable so current setting can be changed if needed.

LM3549 has a fault detection feature that can detect several different fault conditions. In case of a fault error flags are set and FAULT output sends interrupt to control logic. Error flags can be read through I2C interface.

Total brightness can be controlled with PWM input or with master fader register if I2C interface is used.

LM3549 Evaluation board is designed to help getting familiarized with the LM3549. It can be used to measure key parameters of the LM3549 and to speed up design in of the device. The evaluation board has a microcontroller that acts as an USB to I2C interface. Microcontroller is also used to manipulate the digital control signals of the LM3549. LM3549 evaluation board can be powered from the USB interface or from external power supply. If evaluation board is used to measure the electrical parameters of the LM3549 or used with high output currents external power supply needs to be used.

If evalution board is used to check the functionality of the LM3549 with small output currents or to support software development it can be powered directly from USB interface. This document describes how to get the LM3549 evaluation board up and running and how to use evaluation software.

图3. LM3549评估板外形图

图4. LM3549评估板电路图
LM3549评估板材料清单:

详情请见:
http://www.national.com/ds/LM/LM3549.pdf
和
http://www.national.com/an/AN/AN-2062.pdf