Advantech SOM-ETX Design Guide
5.3.2 Design Note
Figure 5.12 shows the connections for SOM-ETX audio signal. We will talk about the
design notes of AUXAL/AUXAR, SNDL/SNDR, and MIC respectively in sections
below. In additional, all AC-coupling capacitor have been implement on SOM
module.
SOM-ETX
AUXAL
MIC
Audio Line in
Audio Line out
MIC in
Audio Connector
AUXAR
SNDL
SNDR
Figure 5-12 Audio Connetions
5.3.2.1 AUXA (line in) and SND (line out)
The AUXA (line in) and SND (line out) signals are AC-coupled and have a maximum
signal level of approximately 1Vrms. Audio sources connected to line inputs are
having capability of driving an external amplifier on the audio line out signals. On the
other hand, headphone or speakers that connected to line outputs are also capable
to drive an external audio power amplifier.
Table 5.10 Audio CODEC Specification
SOM
Module
AC’97
CODEC
AC’97
Compliance
Full Scale Input/Output
Voltage(AUXA/SND)
Nominal Input
/Output Impedance
SOM-
4481
Realtek
ALC202
AC’97 V.2.2
1.2/1.1 Vrms
64k/280 ohm
SOM-
4486
Realtek
ALC202
AC’97 V.2.2
1.2/1.1 Vrms
64k/280 ohm
SOM-
4475
Realtek
ALC201
AC’97 V.2.2
1.2/1.1 Vrms
32k/200 ohm
SOM-
4472
Realtek
ALC202
AC’97 V.2.2
1.2/1.1 Vrms
64k/280 ohm
SOM-
4470
ESS ES1989
Allegro
AC’97 V.2.1
1.0/1.0 Vrms
22k/200 ohm
SOM-
4451
Realtek
ALC201
AC’97 V.2.2
1.2/1.1 Vrms
32k/- ohm
SOM-
4450
Analog Device
AD1881A
AC’97 V.2.1
1.0/1.0 Vrms
20k/500 ohm
Chapter 5 Carrier Board Design Guidelines
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