High-power and high-brightness HB LED driver solution based on MAX16834

The MAX16834 from Maxim is a current-mode high-power 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 PWM controller, it can also drive an N-channel PWM dimming switch. The MAX16834 input voltage ranges from 4.75V to 28V, 3000:1 PWM dimming/analog dimming, and the operating frequency is programmable from 100kHz to 1MHz. It is mainly used in single-string LED LCD backlight, automotive front and rear lighting, precision system RGB LED light source, DC/DC boost/boost-buck converters, etc. This article introduces the main features, block diagram, various application circuits of

the MAX16834, as well as the main features, circuit diagram, bill of materials, and PCB component layout of the MAX16834 evaluation board. 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. . 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 . 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. is also suitable for DCDC 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 main features: _ 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 _ 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 Applications:

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


Diagram 1.MAX16834 block diagram

Figure 2.MAX16834 boost LED driver

Figure 3.MAX16834 boost-buck LED driver (VLED+ < 28V)

Figure 4. MAX16834 boost LED driver with automotive electronic load surge protection

Figure 5. MAX16834 high-side buck LED driver

Figure 6. MAX16834 boost DC/DC converter

Figure 7. MAX16834 boost-buck DC/DC The MAX16834

evaluation

(EV kit) is a fully assembled and tested surface-mount PCB designed to evaluate the MAX16834 pulse-width modulated (PWM) HB LED driver controller in a step-up (boost) configuration and optional step -up/step-down (buck-boost) operation.

The MAX16834 EV kit operates from a DC supply voltage of 7V to 28V and requires up to 5A. The MAX16834 EV kit circuit is configured to deliver up to 1A of current into series LEDs with a maximum forward voltage of 28V.

The MAX16834 EV kit features two different types of dimming control using either an analog linear input voltage or digital PWM input signal to control the LED brightness. This EV kit has an undervoltage lockout (UVLO) feature that disables the EV kit and overvoltage protection that protects the circuit under no-load conditions . The EV kit also features an active-low FLT PCB pad to monitor for open or short-circuit LED conditions at the LED+ and LED- PCB pads. The MAX16834 EV kit is a fully assembled and tested surface-mount board.

MAX16834 Evaluation Board Key Features:

♦ 7V to 28V Wide Supply Voltage Range

♦ Configured for Boost Operation

♦ Configurable for Buck-Boost Operation

♦ 1A Output Current

♦ Analog Linear Dimming Control

♦ PWM Dimming Control

♦ Open/Short-Circuit LED Fault Indicator (FLT)

♦ Demonstrates Output Overvoltage Protection

♦ Optional Load Dump Circuit

♦ Fully Assembled and TestedFigure

8. MAX16834 EV kit circuit

diagramMAX16834 EV kit bill of materials (BOM): Figure 9. MAX16834 EV kit component layout