User Guide

NSB-5
System Module PAMS Technical Documentation
Page 32 Nokia Mobile Phones Ltd. Issue 1 03/01
External Audio Connections
The external audio connections are presented in figure 16. A headset can be connected
directly to the system connector. The headset microphone bias is supplied from COBBA
AUXOUT output and fed to microphone through XMIC line. The 330ohm resistor from
SGND line to AGNDprovides a return path for the bias current.
Figure 13: Combined headset and system connector audio signal
Analog Audio Accessory Detection
In XEAR signal there is a 47 kΩ pullup in the transceiver and 6.8 kΩ pull–down to SGND
in accessory. The XEAR is pulled down when an accessory is connected, and pulled up
when disconnected. The XEAR is connected to the HookDet line (in MAD), an interrupt is
given due to both connection and disconnection. There is filtering between XEAR and
HookDet to prevent audio signal giving unwanted interrupts.
XEAR
SGN
D
47R
10m
100n
100n
HEADDET
H
F
HFC
M
47k
VBB
MIC1
N
MIC1
P
100n
100n
MIC3
N
MIC3
P
XMI
C
220k
MAD
100n
HOOKDET
AUX-
OUT
EAD
CCONT
2k2
27p
Baseband
COBBA–
GJP
220k
LGN
D
+
+
+
R01
C01
C02
C03
L01
Z01
SW01
PC–Board
R01= 100R
C01=33uF
C02=1000pF
C03=22pF
L01=MMZ2012Y6
01BT/TDK
AGND
330R
27p
2k2
AGND AGND AGND
100n
AGND
PD2
AGND
1u
AGND
10u
AGND
27p
VBB VBB
10k
2k2
33R
2k2 47k
100MHz
100R
100R