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TC-L42E3 LED Backlight Control Explanation
The LED Drive circuit receives 24V from the SMPS.
When IC8000 is satisfied of the presence of all the monitored sub-voltages, it provides the
Backlight_On command to turn on the LED drive circuit. This command enters the P-Board via pin
13 of connector P2 and travels to the LCD panel to turn on the LED drive circuit. The backlight
control signal, PWM, is delivered to the LED drive circuit via pin 1 of connector P4 to control the
brightness of the LEDs. The PWM signal is dependent on user settings and picture content. An
artificial intelligence circuit is used to manipulate the PWM signal for picture quality and reduced
power consumption. The LED drive circuit is responsible for controlling the amount of current that
passes through the LEDs.
To avoid catastrophic failures, when the LED backlight control circuit is defective, the
BACKLIGHT_SOS command is output to IC8000 to trigger the shutdown of the TV. The power
LED blinks one time.
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