CS8416
14 APPENDIX A: EXTERNAL
AES3/SPDIF/IEC60958 RECEIVER
COMPONENTS
14.1 AES3 Receiver External Components
The CS8416 AES3 receiver is designed to accept
both the professional and consumer interfaces. The
digital audio specifications for professional use call
for a balanced receiver, using XLR connectors,
with 110 Ω ±20% impedance. The XLR connector
on the receiver should have female pins with a male
shell. Since the receiver has a very high input im-
pedance, a 110 Ω resistor should be placed across
the receiver terminals to match the line impedance,
as shown in Figure 14 and Figure 15. Although
transformers are not required by the AES, they are,
however, strongly recommended.
If some isolation is desired without the use of trans-
formers, a 0.01µF capacitor should be placed in se-
ries with each input pin (RXP0 and RXN0) as
shown in Figure . However, if a transformer is not
used, high frequency energy could be coupled into
the receiver, causing degradation in analog perfor-
mance.
Figure 14 and Figure 15 show an optional DC
blocking capacitor (0.1µF to 0.47 µF) in series with
the cable input. This improves the robustness of the
receiver, preventing the saturation of the trans-
former, or any DC current flow, if a DC voltage is
present on the cable.
In the configuration of systems, it is important to
avoid ground loops and DC current flowing down
the shield of the cable that could result when boxes
with different ground potentials are connected.
Generally, it is good practice to ground the shield
to the chassis of the transmitting unit, and connect
the shield through a capacitor to chassis ground at
the receiver. However, in some cases it is advanta-
geous to have the ground of two boxes held to the
same potential, and the cable shield might be de-
pended upon to make that electrical connection.
Generally, it may be a good idea to provide the op-
tion of grounding or capacitively coupling the
shield to the chassis.
In the case of the consumer interface, the standards
call for an unbalanced circuit having a receiver im-
pedance of 75 Ω ±5%. The connector for the con-
sumer interface is an RCA phono socket. The
receiver circuit for the consumer interface is shown
in Figure . Figure shows an implementation of the
Input S/PDIF Multiplexer using the consumer in-
terface.
The circuit shown in Figure may be used when ex-
ternal RS422 receivers, optical receivers or other
TTL/CMOS logic outputs drive the CS8416 receiv-
er section.
14.2 Isolating Transformer Requirements
Please refer to the application note AN134: AES
and SPDIF Recommended Transformers for re-
sources on transformer selection.
DS578PP2
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