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National Semiconductor Electronic Components Datasheet

LM27964 Datasheet

White LED Driver System

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LM27964 pdf
August 2007
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
www.DataSheeLt4EUD.cso. m
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 I2C com-
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).
Features
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
I2C Compatible Brightness Control Interface
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
Applications
Mobile Phone Display Lighting
Mobile Phone Keypad Lighting
PDAs Backlighting
General LED Lighting
Typical Application Circuit
© 2007 National Semiconductor Corporation 201381
20138101
www.national.com


National Semiconductor Electronic Components Datasheet

LM27964 Datasheet

White LED Driver System

No Preview Available !

LM27964 pdf
Connection Diagram
24 Pin Quad LLP Package
NS Package Number SQA24A
www.DataSheet4U.com
20138102
Pin Descriptions
Pin #s
24
23
19, 22 (C1)
20, 21 (C2)
13, 14, 15, 16
4, 5
6
17
3
12
1
2
7
9, 10, 18, DAP
8, 11
Pin Names
VIN
POUT
C1, C2
Pin Descriptions
Input voltage. Input range: 2.7V to 5.5V.
Charge Pump Output Voltage
Flying Capacitor Connections
D4A, D3A, D2A, D1A LED Drivers - GroupA
D1B, D2B
LED Drivers - GroupB
DKEY
LED Driver - KEYPAD
ISETA
ISETB
ISETK
SCL
Placing a resistor (RSETA) between this pin and GND sets the full-scale LED current for
Group A LEDs. LED Current = 200 × (1.25V ÷ RSETA)
Placing a resistor (RSETB) between this pin and GND sets the full-scale LED current for
Group B LEDs. LED Current = 200 × (1.25V ÷ RSETB)
Placing a resistor (RSETK) between this pin and GND sets the total LED current for the
KEYPAD LEDs. Keypad LED Current = 800 × (1.25V ÷ RSETK)
Serial Clock Pin
SDIO
Serial Data Input/Output Pin
VIO Serial Bus Voltage Level Pin
GND
Ground
NC No Connect
Ordering Information
Order Information
LM27964SQ-I
LM27964SQX-I
LM27964SQ-C
LM27964SQX-C
Current Source
PWM Frequency
10kHz.
23kHz.
Package
SQA24 LLP
SQA24 LLP
Supplied As
1000 Units, Tape & Reel
4500 Units, Tape & Reel
1000 Units, Tape & Reel
4500 Units, Tape & Reel
www.national.com
2


Part Number LM27964
Description White LED Driver System
Manufacturer National Semiconductor
Total Page 14 Pages
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