LM27965_07 Datasheet, PDF (1/14 Pages) National Semiconductor (TI) – Dual Display White LED Driver with I2C Compatible Brightness Control

October 2007
LM27965
Dual Display White LED Driver with I2C Compatible
Brightness Control
General Description
The LM27965 is a highly integrated charge-pump-based du-
al-display LED driver. The device can drive up to 9 LEDs in
parallel with a total output current of 180mA. Regulated inter-
nal current sinks deliver excellent current and brightness
matching in all LEDs.
The LED driver current sinks are split into three independently
controlled groups. The primary group can beconfigurabled
with 4 or 5 LEDs, for backlighting a larger main display and
the second group can be configured with 2 or 3 LEDs, for
backlighing a smaller secondary display. An additional, inde-
pendently controlled led driver is provided for driving an indi-
cator or general purpose LED. The LM27965 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 regula-
tion is chosen based on LED forward voltage, so that effi-
ciency is maximized over the input voltage range.
The LM27965 is available in National's small 24-pin Leadless
Leadframe Package (LLP-24).
Features
■ ^{91% Peak LED Drive Efficiency}
■ ^{No Inductor Required}
■ ^{0.3% Current Matching}
■ ^{Drives LEDs with up to 30mA per LED}
■ ^{180mA of total drive current}
■ ^{I2C Compatible Brightness Control Interface}
■ ^{Adaptive 1× - 3/2× Charge Pump}
■ ^{Resistor-Programmable Current Settings}
■ ^{External Chip RESET Pin}
■ ^{Extended Li-Ion Input: 2.7V to 5.5V}
■ ^{Small low profile industry standard leadless package, LLP}
24 : (4mm x 4mm x 0.8mm)
■ ^{25mm2 total solution size}
■ ^{Two I2C Compatible Chip Address Options: 0x36 for}
LM27965SQ and 0x38 for LM27965SQ-M
Applications
■ ^{Mobile Phone Display Lighting}
■ ^{PDA Backlighting}
■ ^{General LED Lighting}
Typical Application Circuit
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