LGE Internal Use Only
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
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
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Figure 3-5-3. Charge pump Output Current
Signals Description
_LCD_CS 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
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