LM27964 Datasheet | National Semiconductor

Description The LM27964 is a charge-pump-based white-LED driver that is ideal for mobile phone display backlighting. The LM27964 can drive up to 6 LEDs in parallel along with multiple keypad LEDs, with a total output current up to 180m A. Regulated internal current sources deliver excellent current matching in all .. LEDs. The LED driver current sources are split into two independently controlled groups. The primary group (4 LEDs) can be used to backlight the main phone display and the second group (2 LEDs) can be used to backlight a secondary display. A single Keypad LED driver can power up to 16 keypad LEDs with a current of 5m A each. The LM27964 has an I2C patible interface that allows the user to independently control the brightness on each bank of LEDs. The LM27964 works off an extended Li-Ion input voltage range (2.7V to 5.5V). The device provides excellent efficiency without the use of an inductor by operating the charge pump in a gain of 3/2, or in Pass-Mode. The proper gain for maintaining current regulation is chosen, based on LED forward voltage, so that efficiency is maximized over the input voltage range. The LM27964 is available in National's small 24-pin Leadless Leadframe Package (LLP-24). Features - 87% Peak LED Drive Efficiency - 0.2% Current Matching between Current Sinks - Drives 6 LEDs with up to 30m A per LED in two distinct - - - - - - - groups, for backlighting two displays (main LCD and sub LCD) Dedicated Keypad LED Driver with up to 80m A of drive current Independent Resistor-Programmable Current Settings I2C patible Brightness Control Interface Adaptive 1×- 3/2× Charge Pump Extended Li-Ion Input: 2.7V to 5.5V Small low profile industry standard leadless package, LLP 24 : (4mm x 4mm x 0.8mm) LM27964SQ-I LED PWM frequency = 10k Hz, LM27964SQ-C LED PWM frequency = 23k Hz Applications - - - - Mobile Phone Display Lighting Mobile Phone Keypad Lighting PDAs Backlighting General LED Lighting Typical Application Circuit © 2007 National...