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 I

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

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91% Peak LED Drive Efficiency

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No Inductor Required

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0.3% Current Matching

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Drives LEDs with up to 30mA per LED

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180mA of total drive current

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I

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Adaptive 1x - 3/2x Charge Pump

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Resistor-Programmable Current Settings

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External Chip RESET Pin

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Extended Li-Ion Input: 2.7V to 5.5V

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Small low profile industry standard leadless package,

LLP 24 : (4mm x 4mm x 0.8mm)

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25mm

Applications

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Mobile Phone Display Lighting

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PDA Backlighting

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General LED Lighting

Typical Application Circuit

20155001

May 2006

© 2006 National Semiconductor Corporation

DS201550

www.national.com