Design Note - Advantech SOM-ETX Series Design Manual

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
AUXAR
SNDL
SNDR
MIC
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 AC'97
Module CODEC
SOM- Realtek
4481
ALC202
SOM-
Realtek
4486 ALC202
SOM- Realtek
4475 ALC201
SOM- Realtek
4472 ALC202
SOM- ESS ES1989
4470 Allegro
SOM- Realtek
4451
ALC201
SOM- Analog Device
4450 AD1881A
Advantech SOM-ETX Design Guide
Figure 5-12 Audio Connetions
AC'97 Full Scale Input/Output
Compliance Voltage(AUXA/SND)
AC'97 V.2.2 1.2/1.1 Vrms
AC'97 V.2.2 1.2/1.1 Vrms
AC'97 V.2.2 1.2/1.1 Vrms
AC'97 V.2.2 1.2/1.1 Vrms
AC'97 V.2.1 1.0/1.0 Vrms
AC'97 V.2.2 1.2/1.1 Vrms
AC'97 V.2.1 1.0/1.0 Vrms
Chapter 5 Carrier Board Design Guidelines
Audio Connector
Audio Line in
Audio Line out
MIC in
Nominal Input
/Output Impedance
64k/280 ohm
64k/280 ohm
32k/200 ohm
64k/280 ohm
22k/200 ohm
32k/- ohm
20k/500 ohm
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