Datasheet

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SBFS026B − JUNE 2004 − REVISED SEPTEMBER 2007
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24
OUTPUT PORT OPERATION
The audio output port is a four-wire synchronous serial
interface that may operate in either Slave or Master mode.
SDOUTA (pin 64) and SDOUTB (pin 49) are the serial
audio data outputs for SRC A and SRC B, respectively.
Audio data is output at these pins in one of four data
formats: Philips I
2
S, Left-Justified, Right-Justified, or
TDM. The audio data word length may be 16-, 18-, 20-, or
24-bits. For all word lengths, the data is triangular PDF
dithered from the internal 28-bit data path. The data
formats (with the exception of TDM mode) are shown in
Figure 7, while critical timing parameters are shown in
Figure 6 and listed in the Electrical Characteristics table.
The TDM format and timing are shown in Figure 15 and
Figure 16, respectively, while examples of standard TDM
configurations are shown in Figure 17 and Figure 18.
The bit clock is either input or output at BCKOA (pin 63)
and BCKOB (pin 50). In Slave mode, the bit clock is
configured as an input pin, and may operate at rates from
32f
s
to 128f
s
, with a minimum of one clock cycle for each
data bit. The exception is the TDM mode, where the BCKO
must operate at N × 64f
s
, where N is equal to the number
of SRC sections cascaded on the TDM bus. In Master
mode, the bit clock operates at a fixed rate of 64f
s
for all
data formats except TDM, where BCKO operates at the
reference clock frequency. Additional information
regarding TDM mode operation is included in the
Applications Information section of this data sheet.
t
SOH
t
DOPD
t
SOL
t
DOH
LRCKO
BCKO
SDOUT
Figure 6. Output Port Timing
Left Channel
(a)Left−JustifiedDataFormat
(b) Right−Justified Data Format
Right Channel
LRCKO
BCKO
SDOUT
MSB LSB LSBMSB
LRCKO
BCKO
SDOUT
MSB MSB LSBLSB
(c) I
2
SDataFormat
1/f
S
LRCKO
BCKO
SDOUT
MSB LSB MSB LSB
Figure 7. Output Data Formats