Specifications

Intel
®
810E2 Chipset Platform
R
170 Design Guide
7.2.14. AC’97
Checklist Items Recommendations
AC_BITCLK No extra pull-down resistors required.
When nothing is connected to the link, BIOS must set a shut off bit for the internal keeper
resistors to be enabled. At that point, you do not need pull-ups/pull-downs on any of the link
signals.
AC_SYNC No extra pull-down resistors required. Some implementations add termination for signal
integrity. Platform specific.
AC_SDOUT Requires a jumper to 8.2 kΩ pull-up resistor. Should not be stuffed for default operation.
This pin has a weak internal pull-down. To properly detect a safe_mode condition a strong
pull-up will be required to over-ride this internal pull-down.
AC_SDIN[1],
AC_SDIN[0]
Requires pads for weak 10 kΩ pull-downs. Stuff resistor for unused AC_SDIN signal or
AC_SDIN signal going to the CNR connector.
AC_SDIN[1:0] are inputs to an internal OR gate. If a pin is left floating, the output of the OR
gate will be erroneous.
If there is no codec on the system board, then both AC_SDIN[1:0] should be pull-down
externally with resisters to ground.
CDC_DN_ENAB# If the primary codec is down on the motherboard, this signal must be low to indicate the
motherboard codec is active and controlling the AC ’97 interface.
Z
O
AC97 = 60 Ω + 15%
5 mil trace width, 5 mil spacing between traces
Max Trace Length ICH2/Codec/CNR = 14”
7.2.15. Miscellaneous Signals
Checklist
Items
Recommendations
SPKR No extra pull-up resistors. Has integrated pull-up of between 18 kΩ and 42 kΩ. The integrated
pull-up is only enabled at boot/reset for strapping functions; at all other times, the pull-up is
disabled.
A low effective impedance may cause the TCO Timer Reboot function to be erroneously
disabled.
Effective Impedance due speaker and codec circuitry must be greater than 50 k
Ω or a means
to isolate the resistive load from the signal while PWROK is low be found. see following figure.
TP[0] Requires external pull-up resistor to VCCSUS3.3
FS[0] Rout to a testpoint. ICH2 contains an integrated pull-up for this signal. Testpoint used for
manufacturing appears in XOR tree.