User Guide

PAMS Technical Documentation System Module & UI
NHM-8NX
Issue 1 05/02 ãNokia Corporation Page 9
Table 6: Current sources
Internal Signals and Connections
The tables below describe internal signals. The signal names can be found on the sche-
matic for the bf4a PWB.
Audio
Table 7: Internal microphone
Table 8: Internal speaker (Differential output EARP & EARN)
MIDI
Table 9: Connections between UPP and LM4890
Table 10: Connections between UEM/Battery and LM4890
VR7 2.70V 2.78V 2.86V I
max
= 45mA
Signal Min Nom Max Note
IPA1 and IPA2 0mA - 5mA Not used
Signal Min Nom Max Condition Note
MIC1P (Differential input P) - - 100mV
pp
G=20dB 1kΩ to MIC1B
(RC filtered by 220R/4.7uF)
MIC1N (Differential input N) - - 100mV
pp
G=20dB 1kΩ to GND
MICB1 (Microphone Bias) 2.0 V 2.1 V 2.25 V DC
External loading of MICB1 - - 600uA DC
Signal Min
No
m
Max Units Note
Output voltage swing 4.0 - - Vpp Differential output
Load Resistance (EARP to EARN) 26 32 - W
Load Capacitance (EARP to EARN) - - 50 nF
Signal From To Parameter Min. Max. Unit Notes
Shutdown GENIO[14] Shutdown
(p. 5)
Vih
Vil
1.2
-
-
0.4
V
V
LM4890 detec-
tions treshold
levels
Signal name From To Parameter Min. Max. Unit Notes