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U8655
Maintenance Manual
The following table describes the signal definitions.
Category
Description
Digital power supply
Power supply
input
Analog power input
Data
MIPI data
MIPI data
Synchronization
Frame synchronization
signal
clock
Clock signal
MIPI clock
MIPI clock
Control signal
Reset signal
Identification
LCD model identification
signal
LCD model identification
U8666's LCD backlight control:
The U8666 uses a 3.5-inch LCD whose backlight is provided by six LEDs connected in series.
The backlight LEDs are controlled by the backlight driver chip TPS61160A. The ground
resistance of the driver chip pin FB is set to 10 Ω, providing up to 20 mA current to the LEDs
(duty:100%). The backlight brightness (driver output current) is controlled by the PWM
signal.
Issue 1.0 (2012-02-23)
Name in the Circuit
Network
VREG_S3
VREG_L12_2P85
MIPI_DSI_LANE1_P
MIPI_DSI_LANE1_N
MDP_VSYNC_P
MIPI_DSI_CLK_P
MIPI_DSI_CLK_N
LCD_RESET_N
LCD_ID0
LCD_ID1
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
9 Principles and Failure Analysis
MSM7225A GPIO/PM8029
MPP
VREG_S3 (PM8029)
VREG_L12_2P85 (PM8029)
MIPI_DSI_LANE1_P
MIPI_DSI_LANE1_N
GPIO97
MIPI_DSI_CLK_P
MIPI_DSI_CLK_N
GPIO129
GPIO9 (PM8029)
GPIO10 (PM8029)
36
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