LM27965 Datasheet, PDF (1/13 Pages) National Semiconductor (TI) – Dual Display White LED Driver with I2C Compatible Brightness Control

May 2006
LM27965
Dual Display White LED Driver with I2C Compatible
Brightness Control
General Description
The LM27965 is a highly integrated charge-pump-based
dual-display LED driver. The device can drive up to 9 LEDs
in parallel with a total output current of 180mA. Regulated
internal current sinks deliver excellent current and brightness
matching in all LEDs.
The LED driver current sinks are split into three indepen-
dently controlled groups. The primary group can beconfig-
urabled 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 addi-
tional, independently controlled led driver is provided for
driving an indicator 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 regu-
lation is chosen based on LED forward voltage, so that
efficiency is maximized over the input voltage range.
The LM27965 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 LEDs with up to 30mA per LED
n 180mA of total drive current
n I²C Compatible Brightness Control Interface
n Adaptive 1x - 3/2x Charge Pump
n Resistor-Programmable Current Settings
n External Chip RESET Pin
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)
n 25mm² total solution size
Applications
n Mobile Phone Display Lighting
n PDA Backlighting
n General LED Lighting
Typical Application Circuit
© 2006 National Semiconductor Corporation DS201550
20155001
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