Eurotech Appliances VIPER / VIPER-LITE PXA255 - Manual (Page 56)

VIPER Technical Manual Detailed hardware description
© 2007 Eurotech Ltd Issue E 56
Audio
A National Semiconductor LM4549 AC’97 audio CODEC is used to support the audio
features of the VIPER. Audio inputs supported by the LM4549 are stereo line in and a
mono microphone input.
The LM4549 provides a stereo line out that can also be amplified by a National
Semiconductor LM4880 250mW per channel power amplifier, suitable for driving an 8
Ω
load. The LM4549 AC’97 codec may be turned off if it is not required. See the section
357H
Audio power management , page
358H
84 , for details.
Connection to the VIPER audio features is via header PL6. See the table below for pin
assignments and the section
359H
PL6 – Audio connector , page
360H
91 , for connector and
mating connector details.
Function Pin Signal
Signal levels (max) Frequency
response (Hz)
10 MIC input
Microphone 9
7
MIC voltage reference output
Audio ground reference.
1Vrms 20 – 20k
1 Line input left
5 Line input right Line in
3 Audio ground reference
1Vrms 20 – 20k
2 Line output left
6 Line output right Line out
4 Audio ground reference
1Vrms 20 – 20k
8 Amp output left
11 Amp output right Amp out
12 Audio ground reference
1.79V peak ,
1.26Vrms
(8
Ω load) 223mW
20 – 20k
The left and right amp output signals are not AC coupled, these signals must be
AC coupled with 100uF capacitors externally.
VL