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LGE Internal Use Only
Copyright © 011 LG Electronics. Inc. All right reserved.
Only for training and service purposes
3. TECHNICAL BRIEF
3.12.3 MUIC
(Micro USB Integrated IC - Multiplexing USB, UART and audio on a single micro USB connector)
The USB input provides high speed USB connection. The audio inputs feature negative rail signal operation to
realize simple DC coupled headset speakers. The RT8966 provides an internal device detection method by
using the USB ID signal pin and the VBUS voltage. The resistor values and VBUS voltage determine the unique
detection method of each accessory. The host microprocessor adopts I2C to control the switch position and
read the results of the accessory detectioicro USB connecn. The RT8966 can also detect USB chargers,
including dedicated chargers (D+/D-shorted) and high, power, host/hub chargers.
Switches
The RT8966 provides a multiple input multiplexer to support USB high Speed, UART, stereo audio, mono
audio and a microphone. The output of the multiplexer is used to connect to a mini or mtor. When the VBUS
voltage is higher than the VB Detect threshold voltage, the RT8966 can turn on and turn off the paths of USB,
UART and Audio. However, when the VBUS voltage is lower than the VB Detect threshold voltage, the RT8966
can then only turn on and turn off the paths of stereo audio and mono audio. The following table shows the
switch status versus VBUS level.
Table 3.12.1. RT8966GQW SWITCH DETECTION TABLE