High-Power LED Driver with Integrated High-Side LED Current Sense and PWM Dimming MOSFET Driver

The MAX16834 is a current-mode high-brightness LED (HB LED) driver for boost, boost-buck, SEPIC, and high-side 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 high-side 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 buck-boost. Additional features include external enable/disable input, an on-chip oscillator, fault indicator output (active-low 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°C to +125°C temperature range.

Applications

* Architectural and Decorative Lighting (MR16, MR111) * Automotive Rear and Front Lighting * DC-DC Boost/Boost-Buck Converters * Projection System RGB LED Light Sources * Single-String LED LCD Backlighting * Spot and Ambient Lights

* Integration Minimizes BOM for High-Brightness LED Driver with a Wide Dimming Range Saving Space and Cost

* Constant-Frequency, Peak Current-Mode Control with Programmable Slope Compensation

* Integrated PWM Dimming MOSFET Driver

* 3000:1 PWM Dimming/Analog Dimming

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

* Internal 7V Low-Dropout Regulator

* Simple Optimization for Efficiency, Board Space and Input Operating Range

* Supports Boost, Buck-Boost, SEPIC, and High-Side Buck Topologies

* 100kHz to 1MHz Programmable High-Frequency Operation

* External Clock Synchronization Input

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

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

* 20-Pin TQFN-EP and TSSOP-EP Packages

* Protection Features Increase System Reliability

* Programmable UVLO

* Programmable True Differential Overvoltage Protection

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