《电子技术应用》

MAXIM MAX16834 大功率LED驱动方案

2011/12/9 14:30:29

MAXIM公司的MAX16834是一款电流模式高亮度LED(HB LED)驱动器,具有升压、降压升压、SEPIC、高侧降压拓扑结构。除了通过开关控制器控制驱动n沟道功率MOSFET开关,MAX16834还驱动一个n沟道PWM调光开关实现LED PWM调光。MAX16834工作电压范围为4.75V~28V,包括一个3A沉/源栅极驱动器。MAX16834具有可编程的斜率补偿的恒定频率峰值电流模式控制,以控制PWM控制器的占空比。主要用于单串LED LCD背景光,汽车前后端照明,投影系统RGB LED照明源,建筑和装饰照明(MR16, M111),场所和环境照明,以及DC-DC升压/降压转换器。本文介绍了MAX16834主要特性、方框图和各种应用电路包括升压LED驱动器, 升-降压LED驱动器,有汽车负载保护的升压LED驱动器以及高侧降压型LED驱动器, 升压型DC-DC转换器和降压-升压型DC-DC转换器。  

The MAX16834 is a current-mode high-brightness LED (HB LED) driver for boost, buck-boost, SEPIC, and highside buck topologies. In addition to driving an n-channel power MOSFET switch controlled by the switching controller, it also drives an n-channel PWM dimming switch to achieve LED PWM dimming. The MAX16834 integrates all the building blocks necessary to implement a fixed-frequency

HB LED driver with wide-range dimming control.The MAX16834 features constant-frequency peak current-mode control with programmable slope compensation to control the duty cycle of the PWM controller.

A dimming driver designed to drive an external n-channel MOSFET in series with the LED string provides wide-range dimming control up to 20kHz. In addition to PWM dimming, the MAX16834 provides analog dimming using a DC input at REFI. The programmable switching frequency (100kHz to 1MHz) allows design optimization for efficiency and board space reduction. A single resistor from RT/SYNC to ground sets the switching frequency from 100kHz to 1MHz while an external clock signal at RT/SYNC disables the internal oscillator and allows the MAX16834 to synchronize to an external clock. The MAX16834’s integrated highside current-sense amplifier eliminates the need for a separate high-side LED current-sense amplifier in buck-boost applications.

The MAX16834 operates over a wide supply range of 4.75V to 28V and includes a 3A sink/source gate driver for driving a power MOSFET in high-power LED driver applications. It can also operate at input voltages greater than 28V in boost configuration with an external voltage clamp. The MAX16834 is also suitable for DCDC converter applications such as boost or buckboost. Additional features include external enable/disable input, an on-chip oscillator, fault indicator output (FLT) for LED open/short or overtemperature conditions, and an overvoltage protection sense input (OVP+) for true overvoltage protection.

The MAX16834 is available in a thermally enhanced 4mm x 4mm, 20-pin TQFN-EP package and in a thermally enhanced 20-pin TSSOP-EP package and is specified over the automotive -40℃ to +125℃ temperature range.

MAX16834的主要应用:

Single-String LED LCD Backlighting

Automotive Rear and Front Lighting

Projection System RGB LED Light Sources

Architectural and Decorative Lighting (MR16, M111)

Spot and Ambient Lights

DC-DC Boost/Buck-Boost Converters

MAX16834的主要性能:

Wide Input Operating Voltage Range (4.75V to28V)

Works for Input Voltage >28V with External Voltage Clamp on VIN for Boost Converter

3000:1 PWM Dimming/Analog Dimming

Integrated PWM Dimming MOSFET Driver

Integrated High-Side Current-Sense Amplifier for LED Current Sense in Buck-Boost Converter

100kHz to 1MHz Programmable High-Frequency Operation

External Clock Synchronization Input

Programmable UVLO

Internal 7V Low-Dropout Regulator

Fault Output (FLT) for Overvoltage, Overcurrent, and Thermal Warning Faults

Programmable True Differential Overvoltage Protection

20-Pin TQFN-EP and TSSOP Packages


简单应用电路图

图1内部方框图



图2. 升压LED驱动器

图3.升-降压LED驱动器(VLED+<28V)

图4.带有汽车负载保护的升压LED驱动器

图5.高侧降压型LED驱动器

图6.升压型DC-DC转换器

图7.降压-升压型DC-DC转换器

详情请见:
http://datasheets.maxim-ic.com/en/ds/MAX16834.pdf

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