Lcd Back-Light Illumination - LG GD310 Service Manual

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 1μF flying capacitors and two small 1μF capacitors at IN and OUTCP) make
this part ideally suited for small, battery-powered applications.
LCD_BACKLIGHT_EN
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 Cwire) serial digital input. AS
2
registers over the Simple Serial Control™ (S
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.
LGE Internal Use Only
VBAT
4
C101
1uF
5
9
R109
3
0ohms
10
15
C102
R101
1uF
100Kohms
Cwire adds addressing capability for multiple data
2
Cwire™), which is only capable of controlling a single
2
Figure 14. I2C Serial data port control method
- 42 -
U100
7
C1+ C2+
C100
1uF
8
C1- C2-
6
OUTCP
IN
11
D1
12
D2
13
EN_SET D3
14
D4
1
GND D5
2
PGND D6
AAT3169IFO-T1
Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
MLED
MLED1
MLED2
MLED3
MLED4
MLED5
C116
1uF