Lcd Back-Light Illumination - LG GD510 Service Manual

3. Technical brief
GD510 Operational Description
GD510 Operational Description
GD510 Operational Description

3.10. LCD back-light illumination

3.10. LCD back-light illumination
The SC654 is a high efficiency charge pump LED driver using Semtech's proprietary charge pump
technology. Performance is optimized for use in single-cell Li-ion battery applications.
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
3.10. LCD back-light illumination
applications.
The SC654 is a high efficiency charge pump LED driver using Semtech's proprietary charge pump
technology. Performance is optimized for use in single-cell Li-ion battery applications.
Figure 12 LCD Back light unit and Flash LED charge pump IC
The AAT3169 is a write-only single wire interface. It provides access to up to 32 registers that control
Figure 12 LCD Back light unit and Flash LED charge pump IC
device functionality. In this system, two sets of pulse trains are transmitted via the SPIF pin. The first
pulse set is used to set the desired address. After the bus is held high for the address hold period, the
The AAT3169 is capable of driving six LEDs for a total of 180mA from a 2.7V to 5.5V input. The current
next pulse set is used to write the data value. After the data pulses are transmitted the bus is held high
Figure 12 LCD Back light unit and Flash LED charge pump IC
sinks may be operated individually or in parallel for driving higher current LEDs. A low external parts
again for the data hold period to signify the data write is complete. At this point the slave device latches
count (two 1 F flying capacitors and two small 1 F capacitors at IN and OUTCP) make this part ideally
the data into the address that was selected by the first set of pulses. The protocol for using this interface
The AAT3169 is a write-only single wire interface. It provides access to up to 32 registers that control
suited for small, battery powered applications. AnalogicTech's AS2Cwire™ (Advanced Simple Serial
is described in the following subsection.
device functionality. In this system, two sets of pulse trains are transmitted via the SPIF pin. The first
Control™) serial digital input is used to enable, disable and set current for each LED with a 16-level
pulse set is used to set the desired address. After the bus is held high for the address hold period, the
logarithmic scale plus four low-current settings down to 115 A. For optimized efficiency, low-current
next pulse set is used to write the data value. After the data pulses are transmitted the bus is held high
settings require only 65 A of housekeeping current. Each output of the AAT3169 is equipped with
again for the data hold period to signify the data write is complete. At this point the slave device latches
built-in protection for output short-circuits and auto-disable for load short-circuits conditions. Built-in
the data into the address that was selected by the first set of pulses. The protocol for using this interface
soft-start circuitry prevents excessive inrush current during start-up. A low current shutdown feature
is described in the following subsection.
disconnects the load from the input and reduces quiescent current to less than 1 A.
LG Electronics
LG Electronics
LGE Internal Use Only
LCD Backlight
VBAT
C514
1u
LCD_BACKLIGHT_EN
C501 R504
1u
100K
Figure 13 I2C Serial data port control method
Figure 13 I2C Serial data port control method
Figure 13 I2C Serial data port control method
U502
C507
4 7
C1+ C2+
1u
5 8
C1- C2-
6
OUTCP
9
IN
11
D1
12
D2
3 13
EN_SET D3
14
D4
10 1
GND D5
15 2
PGND D6
AAT3169IFO-T1
C512
1u
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