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LGE Internal Use Only
Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
3. Technical Brief
3.10. LCD back-light illumination
The AAT3169 is a low noise, constant frequency charge pump DC/DC converter that uses a tri-mode
load switch (1X), fractional (1.5X), and doubling (2X) conversion to maximize efficiency for white LED
applications. The AAT3169 is capable of driving six LEDs for a total of 180mA from a 2.7V to 5.5V input.
The current sinks may be operated individually or in parallel for driving higher current LEDs. A low
external parts count (two 1
μ
F flying capacitors and two small 1
μ
F capacitors at IN and OUTCP) make
this part ideally suited for small, battery-powered applications.
Figure 13. LCD Back light unit and Flash LED charge pump IC
The current sink input magnitude on the AAT3169 is controlled by AnalogicTech's Advanced Simple
Serial Control (AS
2
Cwire) serial digital input. AS
2
Cwire adds addressing capability for multiple data
registers over the Simple Serial Control™ (S
2
Cwire™), which is only capable of controlling a single
register. The AAT3169 has four registers: Bank1, Bank2, Max Current, and Low Current. Three
addresses are used to control the two registers. Address 0 addresses both registers simultaneously to
allow the loading of both registers with the same data using a single write protocol. Address 1 addresses
Register 1 for D1 to D5 current level settings. Address 2 addresses Register 2 for D6 current level
settings.
Figure 14. I2C Serial data port control method
VBAT
1uF
C100
1uF
C101
C102
1uF
R101
100Kohms
U100
AAT3169IFO-T1
2
15
1
10
14
13
3
12
11
9
6
8
5
7
4
C1+
C2+
C1-
C2-
OUTCP
IN
D1
D2
EN_SET
D3
D4
GND
D5
PGND
D6
1uF
C116
R109
0ohms
MLED5
MLED4
MLED3
MLED2
MLED1
MLED
LCD_BACKLIGHT_EN
