Integrated, 2-Channel, High-Brightness LED Driver with High-Voltage Boost and SEPIC Controller

The MAX16838B is a dual-channel LED driver that integrates both the DC-DC switching boost regulator and two 150mA current sinks. A current-mode switching DC-DC controller provides the necessary voltage to both strings of HB LEDs. The device accepts a wide 4.75V to 40V input voltage range and directly withstands automotive load-dump events. For a 5V ±10% input voltage, connect VIN to VCC. The wide input range allows powering HB LEDs for small-to-medium-sized LCD displays in automotive and display backlight applications.

An internal current-mode switching DC-DC controller supports the boost or SEPIC topologies and operates in an adjustable frequency range between 200kHz and 2MHz. The current-mode control provides fast response and simplifies loop compensation. The device also features an adaptive output-voltage adjustment scheme that minimizes the power dissipation in the LED current- sink paths. The MAX16838B can be combined with the MAX15054 to achieve a buck-boost LED driver with two integrated current sinks.

The channel current is adjustable from 20mA to 150mA using an external resistor. The external resistor sets both channel currents to the same value. The device allows connecting both strings in parallel to achieve a maximum current of 300mA in a single channel. The MAX16838B also features pulsed dimming control with minimum pulse widths as low as 500ns on both channels through a logic input (DIM).

The device includes output overvoltage protection, open-LED/shorted-LED detection, and overtemperature protection. The device is available in 20-pin TSSOP (4.4mm) and TQFN (4mm x 4mm) packages and operates over the -40°C to +125°C automotive temperature range.

Applications

* Automotive Display Backlights * Automotive Lighting Applications * LCD Display Backlights

* High Integration Provides for a Compact Solution

* Integrates 2-Channel, 20mA to 150mA Linear LED Current Sinks

* Internal Slope Compensation and Switching MOSFET

* Flexible IC Fits Many Applications

* Boost or SEPIC Converter Topologies

* Wide 4.75V to 40V or 5V ±10% Input Operating Range

* 200kHz to 2MHz Resistor-Programmable Switching Frequency with External Synchronization

* Wide Contrast Ratio Ideal for High Quality TFT and Head-Up Displays

* PWM Dimming Ratio of 10,000:1 at 200Hz

* Robust with Respect to Temperature and Fault Conditions

* Current Foldback Reference Input

* LED Open/Short Detection and Protection

* Output Overvoltage and Overtemperature Protection

* Thermally Enhanced 20-Pin TSSOP (4.4mm) and TQFN (4mm x 4mm) Packages