User Guide

CC Technical Documentation System Module
NPM-10 (3595)
Issue 2 03/2004 ©2004 Nokia Corporation Confidential Page 31
The BSI fixed resistor value indicates the type and default capacity of a battery; NTC
resistor BTEMP measures the battery temperature.
Temperature and capacity information are needed for charge control. These resistors are
connected to the BSI and BTEMP pins of the battery connector. The P\phone has 100 kΩ
pull-up resistors for these lines so that they can be read by A/D inputs in the phone.
External Audio
NPM-10 (3595) supports fully differential external audio accessory connection. A head-
set and PPH-1 can be directly connected to the system connector. Detection of the
different accessories is made in analog by reading the DC voltage value of the EAD
converter.
Figure 8: Headset interface
Analog Audio Accessory Detection
The accessory is detected by the HeadInt signal when the plug is inserted. Normally when
no plug is present, the internal pull-down on the HF pin pulls down the HeadInt signal.
HeadInt comparator value is 1.9 V. When the plug is inserted, the switch in the
connector is opened and the HeadInt signal is pulled up by the internal pull-up. The 1.9 V
threshold level is reached and the comparator output changes to low state, causing an
interrupt. The reverse is true when the accessory is disconnected: the HeadInt switch is
closed and the HeadInt is pulled down.
Table 25: Truth Table for HookInt and HeadInt
Accessory HookInt HeadInt
Basic Headset, fully differential H H
Button Headset (Switch closed) L H
Button Headset (Switch open) H H
1k0
Hookint
HeadintHeadint
EAD
MICB2
MIC2P
MIC2N
33N
HFCM
HF
Button
UEM
2.1V
2.7V
33N
1k0
/MBUS
MicGnd
1.8V
0.3V
0.8V
3...25k
Mic_bias
0.8V
Not all components are shown