lm27964sqx-c National Semiconductor Corporation, lm27964sqx-c Datasheet

lm27964sqx-c

Manufacturer Part Number

lm27964sqx-c

Description

White Led Driver System With I2c Compatible Brightness Control

Manufacturer

National Semiconductor Corporation

Datasheet

1.LM27964SQX-C.pdf (14 pages)

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LM27964

White LED Driver System with I2C Compatible Brightness

Control

General Description

The LM27964 is a charge-pump-based white-LED driver that

is ideal for mobile phone display backlighting. The LM27964

can drive up to 6 LEDs in parallel along with multiple keypad

LEDs, with a total output current up to 180mA. Regulated in-

ternal current sources deliver excellent current matching in all

LEDs.

The LED driver current sources are split into two indepen-

dently controlled groups. The primary group (4 LEDs) can be

used to backlight the main phone display and the second

group (2 LEDs) can be used to backlight a secondary display.

A single Keypad LED driver can power up to 16 keypad LEDs

with a current of 5mA each. The LM27964 has an I

patible interface that allows the user to independently control

the brightness on each bank of LEDs.

The LM27964 works off an extended Li-Ion input voltage

range (2.7V to 5.5V). 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 main-

taining current regulation is chosen, based on LED forward

voltage, so that efficiency is maximized over the input voltage

range.

The LM27964 is available in National's small 24-pin Leadless

Leadframe Package (LLP-24).

Typical Application Circuit

201381

C com-

Features

■

Applications

■

87% Peak LED Drive Efficiency

0.2% Current Matching between Current Sinks

Drives 6 LEDs with up to 30mA per LED in two distinct

groups, for backlighting two displays (main LCD and sub

LCD)

Dedicated Keypad LED Driver with up to 80mA of drive

current

Independent Resistor-Programmable Current Settings

Adaptive 1×- 3/2× Charge Pump

Extended Li-Ion Input: 2.7V to 5.5V

Small low profile industry standard leadless package, LLP

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

LM27964SQ-I LED PWM frequency = 10kHz,

LM27964SQ-C LED PWM frequency = 23kHz

Mobile Phone Display Lighting

Mobile Phone Keypad Lighting

PDAs Backlighting

General LED Lighting

C Compatible Brightness Control Interface

www.national.com

20138101

August 2007

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