- 38 -
LGE Internal Use Only Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
3. Technical brief
GD510 Operational Description Revision A
LG Electronics 38/113 LGE Property
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.
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
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
next pulse set is used to write the data value. After the data pulses are transmitted the bus is held high
again for the data hold period to signify the data write is complete. At this point the slave device latches
the data into the address that was selected by the first set of pulses. The protocol for using this interface
is described in the following subsection.
Figure 13 I2C Serial data port control method
VBAT
1u
C501
AAT3169IFO-T1
U502
215
110
14
133
12
11
9
6
85
74
C1+ C2+
C1- C2-
OUTCP
IN
D1
D2
EN_SET D3
D4
GND D5
PGND D6
C507
1u
1u
C512
R504
100K
C514
1u
LCD_BACKLIGHT_EN
MLED6
MLED5
MLED4
MLED3
MLED2
MLED1
MLED
LCD Backlight
GD510 Operational Description Revision A
LG Electronics 37/116 LGE Property
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.
Figure 12 LCD Back light unit and Flash LED charge pump IC
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 1ȝF flying capacitors and two small 1ȝF capacitors at IN and OUTCP) make this part ideally
suited for small, battery powered applications. AnalogicTech’s AS2Cwire™ (Advanced Simple Serial
Control™) serial digital input is used to enable, disable and set current for each LED with a 16-level
logarithmic scale plus four low-current settings down to 115ȝA. For optimized efficiency, low-current
settings require only 65ȝA of housekeeping current. Each output of the AAT3169 is equipped with
built-in protection for output short-circuits and auto-disable for load short-circuits conditions. Built-in
soft-start circuitry prevents excessive inrush current during start-up. A low current shutdown feature
disconnects the load from the input and reduces quiescent current to less than 1ȝA.
Figure 13 I2C Serial data port control method
GD510 Operational Description Revision A
LG Electronics 38/113 LGE Property
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.
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
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
next pulse set is used to write the data value. After the data pulses are transmitted the bus is held high
again for the data hold period to signify the data write is complete. At this point the slave device latches
the data into the address that was selected by the first set of pulses. The protocol for using this interface
is described in the following subsection.
Figure 13 I2C Serial data port control method
To Next Page
Loading...
Need help?
General
Weight and Dimensions
