LG KG270 Service Manual - Page 26

Charge pump Output Current, Signals, Description, Output mA/Ch

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3. TECHNICAL BRIEF Signals CS3 SSC0_MTSR SSC0_CLK LCD_RESET MLED MLED1/2 2V8_VIO Description This signal enable to access to the driver IC of LCD. This signal transfer serial data to driver IC. This signal transfer serial clock to driver IC. This signal makes driver IC to HW default status. This signal provide power to white LEDs. This signal be feed back from white LEDs. This signal provides power to LCD modules.(2.8V) The AAT3157 is a low noise, constant frequency charge pump DC/DC converter that uses a trimode load switch (1X), fractional (1.5X), and doubling (2X) conversion to maximize efficiency for white LED applications. The AAT3157 is capable of driving up to three channels of LEDs at 20mA per channel 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 VIN and VOUT) make this part ideally suited for small, battery-powered applications. AnalogicTech's S2Cwire™ (Simple Serial Control™) serial digital input is used to enable, disable, and set current for each LED with 16 settings down to 50µA. The low-current mode supply current can be as low as 50µA to save power. Data 1 2 3 4 5 6 7 8 Output (mA/Ch) 20.0 17.0 14.0 12.0 10.0 8.6 7.0 6.0 Data 9 10 11 12 13 14 15 16 Figure 3-5-3. Charge pump Output Current Output (mA/Ch) 5.0 4.2 3.4 2.8 1.0 0.5 0.1 0.05 - 27 -

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The AAT3157 is a low noise, constant frequency charge pump DC/DC converter that uses a trimode
load switch (1X), fractional (1.5X), and doubling (2X) conversion to maximize efficiency for white LED
applications. The AAT3157 is capable of driving up to three channels of LEDs at 20mA per channel
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 VIN and VOUT) make
this part ideally suited for small, battery-powered applications. AnalogicTech's S2Cwire™ (Simple
Serial Control™) serial digital input is used to enable, disable, and set current for each LED with 16
settings down to 50µA.
The low-current mode supply current can be as low as 50µA to save power.
3. TECHNICAL BRIEF
- 27 -
Figure 3-5-3. Charge pump Output Current
Signals
Description
CS3
This signal enable to access to the driver IC of LCD.
SSC0_MTSR
This signal transfer serial data to driver IC.
SSC0_CLK
This signal transfer serial clock to driver IC.
LCD_RESET
This signal makes driver IC to HW default status.
MLED
This signal provide power to white LEDs.
MLED1/2
This signal be feed back from white LEDs.
2V8_VIO
This signal provides power to LCD modules.(2.8V)
Data
Output (mA/Ch)
Data
Output (mA/Ch)
1
20.0
9
5.0
2
17.0
10
4.2
3
14.0
11
3.4
4
12.0
12
2.8
5
10.0
13
1.0
6
8.6
14
0.5
7
7.0
15
0.1
8
6.0
16
0.05