CS8427 Cirrus Logic, CS8427 Datasheet - Page 20

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

stereo data transfer. The CS8427 offers mono mode
operation for the AES3 receiver and the AES3
transmitter. The receiver and transmitter sections
may be independently set to mono mode through
the MMR and MMT control bits.
9.1.1
The receiver mono mode effectively doubles the
input frame rate, Fsi. The clock output on the
RMCK pin tracks Fsi, and thus is doubled in fre-
quency compared to stereo mode. The receiver will
run at a frame rate of Fsi/2, and the serial audio out-
put port will run at Fsi. Sub-frame A data will be
routed to both the left and right data fields on SD-
OUT. Similarly, sub-frame B data will be routed to
both the left and right data fields of the next word
clock cycle of SDOUT.
Using receiver mono mode is only necessary if the
serial audio output port must run at 96 kHz. If the
CS8427 is kept in normal stereo mode and receives
20
Receiver Mono Mode
ILRCK
ISCLK
SDIN
RXN
RXP
Receiver
Serial
Audio
Input
AES3
Figure 9. Software Mode Audio Data Flow Switching Options
SPD
TXD
MUX
MUX
AES3 data arranged in mono mode, the serial audio
output port will run at 48 kHz, with left and right
data fields representing consecutive audio samples.
9.1.2
In transmitter mono mode, the input port will run at
the audio sample rate (Fso), while the AES3 trans-
mitter frame rate will be at Fso/2. Consecutive left
or right channel serial audio data samples may be
selected for transmission on the A and B sub-
frames, and the channel status block transmitted is
also selectable.
Using transmitter mono mode is only necessary if
the incoming audio sample rate is already at 96kHz
and contains both left and right audio data words.
The “mono mode” AES3 output stream may also
be achieved by keeping the CS8427 in normal ste-
reo mode and placing consecutive audio samples in
the left and right positions of an incoming data
stream with a 48 kHz word rate.
Encoder
Transmitter Mono Mode
AES3
AESBP
Output
Serial
Audio
TXOFF
OLRCK
OSCLK
SDOUT
TXP
TXN
CS8427
DS477PP3