Maxim MAX16834 112W长串LED驱动参考设计

关键词： LED驱动 , MAX16834 , Maxim

Maxim公司的MAX16834是电流模式高亮LED（HB LED）,可采用升压,升压－降压,SEPIC和高边降压拓扑．除了能驱动用于开关控制的N沟功率MOSFET,还能驱动Ｎ沟PWM调光开关，输入工作电压4.75V到28V，工作频率100kHz-1MHz,3000:1 PWM调光/模拟调光，主要用在单串LED LCD背光，汽车前后灯照明，投映系统RGB LED光源，DC/DC升压／升-降压转换器以及MR16,M111照明灯．本文介绍了MAX16834主要特性，方框图，各种应用电路以及采用全陶瓷电容的112W长串LED升压驱动器参考设计特性，电路图，PCB布局图．

The MAX16834 is a current-mode high-brightness LED (HB LED) driver for boost, boost-buck, 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 boost-buck 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 DC/DC converter applications such as boost or boostbuck.

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主要特性:

_ Wide Input Operating Voltage Range (4.75V to 28V)

_ 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 Boost-Buck 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-EP Packages

MAX16834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/Boost-Buck Converters

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图1. MAX16834方框图

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Boost LED Driver

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