Audio Codec '97

AC ‘97 Component Specification Revision 2.3 Rev 1.0
100
9.2.3 Data Output and Input Times
Figure 33. Data Output and Input Timing Diagram
Parameter Symbol Min Typ Max Units
Output Valid Delay from rising edge of BIT_CLK tco - - 15 ns
Note: 47.5-75pF external load as per Table 62
Table 56. AC-link Output Valid Delay Timing Parameters
Parameter Symbol Min Typ Max Units
Input Setup to falling edge of BIT_CLK t
setup
10 - - ns
Input Hold from falling edge of BIT_CLK t
hold
10 - - ns
Table 57. AC-link Input Setup and Hold Timing Parameters
Parameter Symbol Min Typ Max Units
BIT_CLK combined rise or fall plus flight time (Primary
Codec to Controller or Secondary)
- - 7 ns
SDATA combined rise or fall plus flight time (Output to
Input)
- - 7 ns
Note: Combined rise or fall plus flight times are provided for worst case scenario modeling purposes
Table 58. AC-link Combined Rise or Fall plus Flight Timing Parameters
The original AC ‘97 1.03 Specification specified SDATA and SYNC to BIT_CLK setup and hold times for point-to-
point Controller to Codec connections. The multiple Codec configurations defined by AC ‘97 2.x introduce
Secondary Codecs that derive their AC-link timing from a Primary Codec’s BIT_CLK. Riser solutions under
development define system implementations where AC-link signal trace lengths can run up to ~15 inches, with total
external capacitive loads of 50 pF or greater. Both of these can impact SDATA and SYNC to BIT_CLK timing
relationships, as well as the strength of the AC-link output pin drivers.
The typical Controller or Codec updates an AC-link output signal on the rising edge of BIT_CLK, drives it valid
prior to BIT_CLK falling, and holds it valid for the entire duration of BIT_CLK low. The typical Controller or
Codec latches AC-link input signals on the falling edge of BIT_CLK. The new Output Valid Delay timing
parameters and reduced Input Setup and Hold times help to allow AC-link operation for multiple Codec and/or riser
implementations.
BIT_CLK
SDATA_OUT
SDATA_IN
SYNC
t
setup
tco
t
hold
V
ih
V
il
V
oh
V
ol