
Maxim Integrated
General Description
The MAX8790 is a high-efficiency driver for white lighte mitting 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 MAX8790 has a wide input-voltage range from 4.5V to 26V, and provides a fixed 20mA or adjustable 15mA to 25mA 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 25mA, 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
Automotive Systems
Handy Terminals