MAXIM MAX16834 大功率LED驅動方案

MAXIM公司的MAX16834是一款電流模式高亮度LED（HB LED）驅動器，具有升壓、降壓升壓、SEPIC、高側降壓拓撲結構。除了通過開關控制器控制驅動n溝道功率MOSFET開關，MAX16834還驅動一個n溝道PWM調光開關實現LED PWM調光。MAX16834工作電壓范圍為4.75V~28V，包括一個3A沉/源柵極驅動器。MAX16834具有可編程的斜率補償的恒定頻率峰值電流模式控制，以控制PWM控制器的占空比。主要用于單串LED LCD背景光，汽車前后端照明，投影系統RGB LED照明源，建筑和裝飾照明(MR16, M111)，場所和環境照明，以及DC-DC升壓/降壓轉換器。本文介紹了MAX16834主要特性、方框圖和各種應用電路包括升壓LED驅動器, 升-降壓LED驅動器,有汽車負載保護的升壓LED驅動器以及高側降壓型LED驅動器, 升壓型DC-DC轉換器和降壓-升壓型DC-DC轉換器。

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的主要應用：

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


簡單應用電路圖

圖1內部方框圖



圖2. 升壓LED驅動器

圖3.升-降壓LED驅動器（VLED+28V）

圖4.帶有汽車負載保護的升壓LED驅動器

圖5.高側降壓型LED驅動器

圖6.升壓型DC-DC轉換器

圖7.降壓-升壓型DC-DC轉換器

詳情請見：
http://datasheets.maxim-ic.com/en/ds/MAX16834.pdf