LM27966 Datasheet, PDF (1/13 Pages) National Semiconductor (TI) – White LED Driver with I2C Compatible Interface

August 2006
LM27966
White LED Driver with I2C Compatible Interface
General Description
The LM27966 is a highly integrated charge-pump-based
display LED driver. The device can drive up to 6 LEDs in
parallel with a total output current of 180mA. Regulated
internal current sources deliver excellent current and bright-
ness matching in all LEDs.
The LED driver current sources are split into two indepen-
dently controlled groups. The primary group, which can be
configured with 4 or 5 LEDs, can be used to backlight the
main phone display. An additional, independently controlled
led driver is provided for driving an indicator or other general
purpose LED function. The LM27966 has an I²C compatible
interface that allows the user to independently control the
brightness on each bank of LEDs.
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 regu-
lation is chosen, based on LED forward voltage, so that
efficiency is maximized over the input voltage range.
The LM27966 is available in National’s small 24-pin Lead-
less Leadframe Package (LLP-24).
Features
n 91% Peak LED Drive Efficiency
n No Inductor Required
n 0.3% Current Matching
n Drives 6 LEDs with up to 30mA per LED
n 180mA of total driver current
n I²C Compatible Brightness Control Interface
n Adaptive 1x- 3/2x Charge Pump
n Resistor-Programmable Current Settings
n External Chip RESET Pin (RESET)
n Extended Li-Ion Input: 2.7V to 5.5V
n Small low profile industry standard leadless package,
LLP 24 : (4mm x 4mm x 0.8mm)
Applications
n Mobile Phone Display Lighting
n PDAs Backlighting
n General LED Lighting
Typical Application Circuit
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