Circuit Descriptions, Abbreviation List, and IC Data Sheets
EN 87LC8.1U LA 9.
LED2
The LED2 control signal controls the secondary LED, and is
controlled by the Standby Controller. Similar, a low signal turns
on the LED, while a high signal turns off the LED. The LED
blinks in protection mode.
LIGHT_SENSOR
The LIGHT_SENSOR signal is an ADC input from the ambient
light sensor. The converted digital value is used in video and
picture quality improvement algorithms; refer to Video/PQ HSI
for the details.
FLASH_MJC_WE
The MJC_FLASH_WE signal is the write enable signal for the
MT8280 flash IC. This signal is hardware wise by default write
enabled but is put to disabled after it is written with a valid
software image file.
PANEL
The PANEL signal is used for service and is detected only at
startup. When activated, the system will go into PANEL mode.
PWRDET
The PWRDET signal detects the power status of the +3V3
supply at startup. The usage of this signal is described in
chapter 5 “Service Modes, Error Codes, and Fault Finding”.
POWER_DOWN
The POWER_DOWN signal is an input from the power-down
detection circuit. For the Standby Controller, this signal is used
to detect the presence of +12V during the startup process.
SCL + SDA
I
2
C signals.
SDM
The SDM signal is used for service and is detected only at
startup. When activated, the system will go into SDM mode.
STANDBYn
The STANDBYn signal is used to control the system power
status, which is used to put the power supply unit to standby or
normal operation. This signal is controlled by the Standby
Controller.
SYS_EEPROM_WE
The SYS_EEPROM_WE signal is the write enable signal for
the system EEPROM IC. The signal is connected to the active
low Write Control pin of the EEPROM via a transistor inverter.
This signal is only active when the system is conducting a write
operation to the system EEPROM.
+12VDISP_DETECT (RESERVED)
The +12VDISP_DETECT signal is an input from the display
timing controller power detection circuit. This signal is used to
detect any power faults on the mentioned power line.
9.9.2 Audio Control Signals
ANTI_PLOP
The ANTI_PLOP signal is used as an as anti-plop control for
the audio muting circuit.
DC_PROT
The DC_PROT signal is used to detect DC voltage level fault
condition at the speaker output to send the system into
protection in order to protect the audio amplifier and speakers.
HEADPHONE_DETECT
The HEADPHONE_DETECT signal is used to detect the
presence of a headphone connection to the Side AV
headphone socket. When a headphone connection is detected,
the speaker output should be muted.
MUTEn
The MUTEn signal is used as the mute control to the
TDA8932BT class-D audio amplifier in an open drain
application.
ANA-DIG_AUDIO_SELECT (RESERVED)
The ANA-DIG_AUDIO_SELECT signal is used as a gain
selector for audio pre-amplifier. The purpose is to halve the
gain in the case of digital inputs, which includes HDMI and
digital TV inputs. The usage of this control signal is reserved,
so it should be set as high impedance during normal operation.
9.9.3 Display Control Signals
ANA-DIG_DIM_SELECT (RESERVED)
The ANA-DIG_DIM_SELECT control signal is used to select
between digital PWM or analog DC backlight dimming method
based on the display type (display option), by acting as a
control signal to a 2:1 analog switch. By default, only digital
PWM backlight dimming will be used. The analog DC backlight
dimming is a provision for future displays which employs the
latter methodology.
BACKLIGHT_BOOST
The BACKLIGHT_BOOST signal is a PWM output to the
backlight boost circuit for display control.
BACKLIGHT_ON_OFF
The BACKLIGHT_ON_OFF signal is used to turn the display
backlight on and off.
CTRL_DISP1_uP
The CTRL_DISP1_uP signal is reserved for use with SDI PDP
display control. When other displays are used, this port should
be tri-stated.
CTRL_DISP4_uP
The CTRL_DISP4_uP signal is reserved for use with FHP PDP
display control. When other displays are used, this port should
be tri-stated.
LCD_PWR_ON
The LCD_PWR_ON signal is used to turn the supply to the
display timing controller board on and off.
PWM_DIMMING
The PWM_DIMMING signal is a PWM output to the backlight
dimming circuit for display control.
9.9.4 HDMI Control Signals
HDMI_RESET
The HDMI_RESET signal is used to reset the Sil9185 HDMI
switch.
CEC
The CEC control signal is used as the system CEC control line.
CEC is an AV systems control protocol derived from P50
adapted for HDMI control. This signal is connected to both
MT5382 and the Standby Controller, with the latter handling the
standby mode wake-up commands and the former handling all
normal operation commands.
DDC_R
ESET
The DDC_RESET signal is used for HDMI DDC data reset
purpose during HDMI signal detection.
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