General Description

The MAX8790A is a high-efficiency driver for white light emitting diodes (LEDs). It is designed for large liquid crystal displays (LCDs) that employ an array of LEDs as the light source. A current-mode step-up controller drives up to six parallel strings of multiple series-connected LEDs. Each string is terminated with ballast that achieves ±1.5 current regulation accuracy, ensuring even brightness for all LEDs. The MAX8790A has a wide input-voltage range from 4.5V to 26V, and provides a fixed 20mA or adjustable 15mA to 27mA full-scale LED current.

Features

● Drives Six Parallel Strings with Multiple SeriesConnected LEDs per String

● ±1.5 Current Regulation Accuracy Between Strings

● Low 450mV Feedback Voltage at Full Current Improves Efficiency

● Step-Up Controller Regulates the Output Just Above the Highest LED String Voltage

● Full-Scale LED Current Adjustable from 15mA to 27mA, or Preset 20mA

● Wide 100:1 Dimming Range

● Programmable Dimming Control: Direct DPWM or Analog Dimming

● Built-In PLL for Synchronized Dimming Control

● Open and Short LED Protections

● Output Overvoltage Protection

● Wide Input Voltage Range from 4.5V to 26V

● External MOSFET Allows a Large Number of LEDs per String

● 500kHz/750kHz/1MHz Switching Frequency

● Small, 20-Pin, 4mm x 4mm Thin QFN Package

Applications

● Notebook, Subnotebook, and Tablet Computer Displays

● Handy Terminals