ADAV803AST Analog Devices Inc, ADAV803AST Datasheet - Page 24

• Manufacturer Part Number: ADAV803AST
• Manufacturer: Analog Devices Inc

Specifications of ADAV803AST

• Single Supply Voltage (typ): 3.3V
• Single Supply Voltage (min): 3V
• Single Supply Voltage (max): 3.6V
• Package Type: LQFP
• Lead Free Status / RoHS Status: Not Compliant

ADAV803
Serial Digital Audio Transmission Standards
The ADAV803 can receive and transmit S/PDIF, AES/EBU, and
IEC-958 serial streams. S/PDIF is a consumer audio standard,
and AES/EBU is a professional audio standard. IEC-958 has
both consumer and professional definitions. This data sheet is
not intended to fully define or to provide a tutorial for these
standards. Contact the international standards-setting bodies
for the full specifications.
All these digital audio communication schemes encode audio
data and audio control information using the biphase-mark
method. This encoding method minimizes the dc content of the
transmitted signal. As can be seen from Figure 43, 1s in the
original data end up with midcell transitions in the biphase-
mark encoded data, while 0s in the original data do not. Note
that the biphase-mark encoded data always has a transition
between bit boundaries.
Digital audio-communication schemes use preambles to
distinguish among channels (called subframes) and among
longer-term control information blocks (called frames). Pream-
bles are particular biphase-mark patterns, which contain encoding
violations that allow the receiver to uniquely recognize them.
These patterns and their relationship to frames and subframes
are shown in Table 8 and Figure 44.
Table 8. Biphase-Mark Encode Preamble
X
Y
Z
The biphase-mark encoding violations are shown in Figure 45.
Note that all three preambles include encoding violations.
(2 TIMES BIT RATE)
X
BIPHASE-MARK
LEFT CH
Biphase Patterns
11100010 or 00011101
11100100 or 00011011
11101000 or 00010111
FRAME 191
CLOCK
Y
DATA
DATA
RIGHT CH
Figure 44. Preambles, Frames, and Subframes
Figure 43. Biphase-Mark Encoding
Z
SUBFRAME
0
LEFT CH
PREAMBLES
FRAME 0
1
Y
SUBFRAME
RIGHT CH
1
Channel
Left
Right
Left and CS block start
1
X
LEFT CH
0
FRAME 1
Y
RIGHT CH
0
Rev. A | Page 24 of 60
Ordinarily, the biphase-mark encoding method results in a
polarity transition between bit boundaries.
The serial digital audio communication scheme is organized
using a frame and subframe construction. There are two
subframes per frame (ordinarily the left and right channel).
Each subframe includes the appropriate 4-bit preamble, up to
24 bits of audio data, a validity (V) bit, a user (U) bit, a channel
status (C) bit, and an even parity (P) bit. The channel status bits
and the user bits accumulate over many frames to convey
control information. The channel status bits accumulate over a
192 frame period (called a channel status block). The user bits
accumulate over 1176 frames when the interconnect is imple-
menting the so-called subcode scheme (EIAJ CP-2401). The
organization of the channel status block, frames, and subframes
is shown in Table 9 and Table 10. Note that the ADAV803
supports the professional audio standard from a software
point of view only. The digital interface supports only
consumer mode.
Table 9. Consumer Audio Standard
Address
N
N + 1
N + 2
N + 3
N + 4
N + 5 to
(N + 23)
1
N = 0x20 for receiver channel status buffer.
N = 0x38 for transmitter channel status buffer.
PREAMBLE X
PREAMBLE Y
PREAMBLE Z
1
7
Reserved
Channel
Status
Channel Number
6
Reserved
1
1
1
Figure 45. Preambles
5
Accuracy
1
1
1
Clock
Emphasis
1
1
1
Category Code
4
Data Bits
Reserved
0
0
0
0
0
1
3
Sampling Frequency
0
1
0
2
Copy-
right
Source Number
1
0
0
Word Length
0
0
0
1
Non-
Audio
0
Pro/
Con
= 0