
Maxim Integrated
General Description
The MAX1578/MAX1579 provide four regulated outputs to meet all the voltage requirements for small activematrix TFT-LCD displays in handheld devices where minimum external components and high efficiency are required. Each device consists of three advanced charge pumps for LCD bias power and a step-up converter for driving up to 8 series white LEDs for backlighting. The input voltage range is from 2.7V to 5.5V.
FEATUREs
♦ Four Regulators in One Package
♦ Bias Power Using Charge Pumps
+5V at 25mA for Source Driver
+15V at 100µA for VON
-10V at 100µA for VOFF
No External Diodes Required
Output Sequencing
POS, NEG, and MAIN Are Autodischarged
During Shutdown
♦ LED Backlight Power Using Boost Converter
Series LED Connection for Uniform Illumination
Supports Up to 8 LEDs at 25mA (max)
900mW (max) Power
PWM or Analog Dimming Control
Overvoltage Protection
Low Input/Output Ripple
Soft-Start with Zero Inrush Current
Fast 1MHz PWM Operation for Small
Component Size
Temperature Derating Function (MAX1579)
♦ High Efficiency
Bias: 83% (5.0V at 25mA, 15V/-10V at 100µA)
LED: 84% (6 LEDs at 20mA)
♦ Uses Only Ceramic Capacitors and Only One
Inductor
♦ Independent Enable Inputs for LED and Bias
Power
♦ Thermal-Shutdown Protection
♦ 1µA Shutdown Current
♦ Tiny 4mm x 4mm Thin QFN Package
APPLICATIONs
PDAs, Palmtops
Smart Phones
Internet Appliances
LCD Displays with
White LED Backlight