Voice Call - LG CF360 Service Manual

3. TECHNICAL BRIEF

3.3.4 Voice Call

A. Voice call Downlink Mode(Receiver, Speaker, Headset)
This section provides a detailed description of the Voice Call RX functions.
The voice decoder accepts a serial input stream of linear PCM coded speech. The receive band-
pass filter is the next step in the CODEC receive path. Following the filter is the DAC, followed by
a PGA enabling to adjust or trim the circuit in the product for different sensitivity of the earphone
and spread in the RX path. The final step in the receive path is the auxiliary output. The auxiliary
audio amplifier is intended to drive low impedance headphones. The earphone amplifier and the
auxiliary audio outputs can be powered down (muted) via I2C. Both the earphone driver and one
of the auxiliary drivers can simultaneously provide an output signal during voice decoding.
• Receiver Mode : BEARP/N Port
• Loud Speaker / Video Telephony Mode : AB3100 SPK Amp
•Headset Mode : Auxiliary audio amplifier
LGE Internal Use Only
Figure 3-3-4. Voice call Downlink Scheme
Receiver(32Ω)
AUDIO AMP(TPA6205)
AUXO1/2
AUDIO AMP(MAX9724D)
- 50 -
SPKR/N
Speaker(8Ω)
Head Phone
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