
DSD1792
SLES067B MARCH 2003 REVISED NOVEMBER 2006
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17
AUDIO DATA INTERFACE
Audio Serial Interface
The audio interface port is a 3-wire serial port. It includes PLRCK (pin 4), PBCK (pin 6), and PDATA (pin 5). PBCK is the
serial audio bit clock, and it is used to clock the serial data present on PDATA into the serial shift register of the audio
interface. Serial data is clocked into the DSD1792 on the rising edge of PBCK. PLRCK is the serial audio left/right word
clock.
The DSD1792 requires the synchronization of PLRCK and the system clock, but does not need a specific phase relation
between PLRCK and the system clock.
If the relationship between PLRCK and the system clock changes more than
±6 PBCK, internal operation is initialized within
1/fS and analog outputs are forced to the bipolar zero level until resynchronization between PLRCK and the system clock
is completed.
PCM Audio Data Formats and Timing
The DSD1792 supports industry-standard audio data formats, including standard right-justified, I2S, and left-justified. The
data formats are shown in Figure 28. Data formats are selected using the format bits, FMT[2:0], in control register 18. The
default data format is 24-bit I2S. All formats require binary 2s complement, MSB-first audio data. Figure 27 shows a detailed
timing diagram for the serial audio interface.
PDATA
t(BCH)
50% of VDD
PBCK
PLRCK
t(BCL)
t(LB)
t(BCY)
t(DS)
t(DH)
50% of VDD
t(BL)
PARAMETERS
MIN
MAX
UNITS
t(BCY)
PBCK pulse cycle time
70
ns
t(BCL)
PBCK pulse duration, LOW
30
ns
t(BCH)
PBCK pulse duration, HIGH
30
ns
t(BL)
PBCK rising edge to PLRCK edge
10
ns
t(LB)
PLRCK edge to PBCK rising edge
10
ns
t(DS)
PDATA Setup time
10
ns
t(DH)
PDATA hold time
10
ns
—
PLRCK clock data
50%
± 2 bit clocks
Figure 27. Timing of Audio Interface