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Only for training and service purposes
3. Technical brief
3.3.4 Voice Call
A. Voice call Downlink Mode (Receiver, Speaker, Headset)
Figure 3-3-4. Voice call Downlink Scheme
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 Æ Receiver(32)
• Loud Speaker / Video Telephony Mode : AB3000 SPK Amp Æ SPKRP/N
Æ AUDIO AMP(MAX9877) Æ Speaker(8)
• Headset Mode : Auxiliary audio amplifier Æ AUXO1/2
Æ AUDIO AMP(MAX9877) Æ Head Phone
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