Analog Ground; Figure 16. Hands-Free Audio Connectivity; Figure 17. Gnd To Agnd Connectivity - Motorola c18 Developer's Manual

c18_Vcc
Mute
P.A
SPKR
Vdd
MIC
3.7.4

Analog Ground

For optimal audio performance, all audio circuits external to the c18 should be referenced to the Analog Ground (AGND) pin.
The connection between AGND and GND is implemented inside the c18 module.
The maximum allowed AGND current is 0.2 A.
Note
98-08901C63-A
Customer Product
1uF
Momentary
4.7K
GND
1uF

Figure 16. Hands-free Audio Connectivity

Customer Side
Digital
Ground
PS

Figure 17. GND to AGND Connectivity

c18_Vcc
100ohm
Audio_Out_ON/OFF
ON/OFF
Switch
2.8V
37K
Audio In
AGND
Analog
Ground
0.1uF
AUXOP
AUXON
680ohm
0.1uF
MSM5100
GND
0.1uF
AUXIP
AUXIN
0.1uF
GND
c18
Analog
Circuits
Logic
Digital
Circuits
Ground
Hardware Description
c18
31