User Guide

GM47/48 Design Guidelines
BA/SEM/MSC 02:0006 Rev PA1 14
3.5 Audio Connections
Audio connections for both of the analogue paths are shown below.
3.5.1 Analogue Audio
Pin Signal Dir. Description
57 AFMS O Audio From Mobile Station
59 ATMS I Audio To Mobile Station
60 AGND - Ground (return) for analogue audio
ATMS and AFMS are the audio input and output for the module.
Figure 3.3 shows the connection of the analogue audio signals ATMS
and AFMS to the CODEC. An Advanced Portable Hands Free
accessory is also shown to clarify the connections.
Simplified Circuit
CODEC
ATMS
MIC
AGND
AFMS
Audio Out
<20 ohms
Bias
0V or 2V or 2.5V
Audio In
70K Ohms
2.7K
Switch
2.2u
Speaker
GM47
Figure 3.3. Analogue Audio Signal Connections.
It shall be possible to use the analogue audio signals in different modes.
• Hands-Free - This is the state referred to as Audio To Mobile
Station ATMS and Audio From Mobile Station AFMS, which