LM27965| Datasheet

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LM27965 Dual Display White LED Driver System 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 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 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, 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 regulation 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 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

20155001

2007 National Semiconductor Corporation

201550

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