SigmaTel, Inc.
1. PIN/SIGNAL DESCRIPTIONS
1.1 Digital I/O
Data Sheet
STAC9721
These signals connect the STAC9721/23 to its AC'97 controller counterpart, an external crystal, multi-
codec selection and external audio amplifier.
Table 3. Digital Signal List
Signal Name
Type
Description
RESET #
XTL_IN
XTL_OUT
SYNC
I
I
AC'97 Master H/W Reset
24.576 MHz Crystal
O
I
24.576 MHz Crystal
48 kHz fixed rate sample sync
BIT_CLK
SDATA_OUT
SDATA__IN
CID0
O
I
12.288 MHz serial data clock
Serial, time division multiplexed, AC'97 input stream
Serial, time division multiplexed, AC'97 output stream
Multi-Codec ID select – bit 0
O
I
CID1
I
Multi-Codec ID select – bit 1
EAPD
O
External Amplifier Power Down
# denotes active low
7
04/07/00
04/07/00
ETC [ ETC ]
