STAC9752A Datasheet, PDF (36/106 Pages) Integrated Device Technology – AC’97 2.3 CODECS WITH STEREO MICROPHONE & UNIVERSAL JACK

STAC9752A/9753A
AC’97 2.3 CODECS WITH STEREO MICROPHONE & UNIVERSAL JACK
PC AUDIO
5.3.1.
SYNC
asserted
SYNC
detected by
codec
first
SDATA_OUT
bit of frame
SYNC
B IT _ C L K
SDATA_OUT
valid
Frame
End of previous audio frame
slot1
slot2
valid time slot, the AC‘97 Controller always stuffs all trailing non-valid bit positions of the 20-bit slot
with 0s.
As an example, consider an 8-bit sample stream that is being played out to one of the STAC9752A/
9753A DACs. The first 8-bit positions are presented to the DAC (MSB justified) followed by the next
12 bit-positions which are stuffed with 0s by the AC‘97 Controller. This ensures that regardless of the
resolution of the implemented DAC (16, 18 or 20-bit), no DC biasing will be introduced by the least
significant bits.
When mono audio sample streams are output from the AC‘97 Controller it is necessary that BOTH
left and right sample stream time slots be filled with the same data.
Slot 0: TAG / CODEC ID
Table 7. Output Slot 0 Bit Definitions
Bit
15
14
13
12-3
12
11
10
9
8
7
6
5
4
3
2
1-0
Description
Frame Valid
Slot 1 Primary CODEC Valid Command Address bit (Primary CODEC only)
Slot 2 Primary CODEC Valid Command Data bit (Primary CODEC only)
Slot 3-12 Valid Data bits
Slot 3: PCM Left channel
Slot 4: PCM Right channel
Slot 5: Modem Line 1 (not used on STAC9752A/9753A)
Slot 6: Alternative PCM1 Left
Slot 7: Alternative PCM2 Left
Slot 8: Alternative PCM2 Right
Slot 9: Alternative PCM1 Right
Slot 10: SPDIF Left
Slot 11: SPDIF Right
Slot 12: Audio GPIO
Reserved (Set to 0)
2-bit CODEC ID field (00 reserved for Primary; 01, 10, 11 indicate Secondary)
Note: The DAC can be assigned to slots 3&4, 6&9, 7&8, or 10&11.
IDT™
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AC’97 2.3 CODECS WITH STEREO MICROPHONE & UNIVERSAL JACK
STAC9752A/9753A
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