CS8427 Cirrus Logic, CS8427 Datasheet - Page 50

• Manufacturer Part Number: CS8427
• Description: 96 kHz Digital Audio Interface Transceiver
• Manufacturer: Cirrus Logic

18. APPENDIX A: EXTERNAL
This section details the external components re-
quired to interface the AES3 transmitter and re-
ceiver to cables and fiber-optic components.
18.1 AES3 Transmitter External
The output drivers on the CS8427 are designed to
drive both the professional and consumer interfac-
es. The AES3 specification for professional/broad-
cast use calls for a 110 Ω source impedance and a
balanced drive capability. Since the transmitter
output impedance is very low, a 110 Ω resistor
should be placed in series with one of the transmit
pins. The specifications call for a balanced output
drive of 2-7 volts peak-to-peak into a 110 Ω load
with no cable attached. Using the circuit in
22, the output of the transformer is short-circuit
protected, has the proper source impedance, and
50
AES3/SPDIF/IEC60958
COMPONENTS
TRANSMITTER AND RECEIVER
CS8427
Components
Figure 22. Professional Output Circuit
TXN
TXP
110 Ω
CS8427
Figure 24. TTL/CMOS Output Circuit
TXN
TXP
1
XLR
Figure
provides a 5 volt peak-to-peak signal into a 110 Ω
load. Lastly, the two output pins should be attached
to an XLR connector with male pins and a female
shell, and with pin 1 of the connector grounded.
In the case of consumer use, the IEC60958 specifi-
cations call for an unbalanced drive circuit with an
output impedance of 75 Ω and a output drive level
of 0.5 volts peak-to-peak ±20% when measured
across a 75 Ω load using no cable. The circuit
shown in
vides the proper output impedance and drive level
using standard 1% resistors. The connector for a
consumer application would be an RCA phono
socket. This circuit is also short circuit protected.
The TXP pin may be used to drive TTL or CMOS
gates as shown in
used for optical connectors for digital audio since
they usually have TTL or CMOS compatible in-
puts. This circuit is also useful when driving multi-
ple digital audio outputs since RS422 line drivers
have TTL compatible inputs.
CS8427
Figure 23. Consumer Output Circuit
TTL or
CMOS Gate
Figure 23
TXP
TXN
374 Ω
90.9 Ω
Figure
only uses the TXP pin and pro-
24. This circuit may be
CS8427
DS477PP3
RCA
Phono