CS4281 Datasheet, PDF (33/36 Pages) Cirrus Logic – CrystalClear PCI Audio interface

CS4281
CrystalClear™ PCI Audio Interface
CLKRUN# - Optional System Clock Control
CLKRUN# is an optional PCI signal defined for mobile operations and is only available on the
CS4280-CQ (128-pin package). This pin is redefined from supply ground to an input with an
open drained output. If maintained at a logic 0, the open drained output is never required to
drive the CLKRUN# signal. In the CS4280 layout, this pin will be tied to ground. Note:
CLKRUN# is not available on the add-in card connector
GPIO3 - General Purpose Input/Output 3
GPIO3 pin of the CS4281 powers up high impedance. High impedance pins connected to the
supply rail results in no damage or excess current being drawn by that pin.
Summary
The new features included in the CS4281 (CLKRUN#, VAUX, TESTSEL, and ISA IRQs) are not usable
when the CS4281 is placed in a CS4280 PWB footprint. The CS4281 maintains the same functionality as
the CS4280 from a user perspective. The CS4281 is NOT backward compatible with the CS4280 software
drivers. A driver upgrade is required to use the CS4281. The upgraded driver will contain support for both
the CS4280 and the CS4281 for those customers that have both devices in their product lines.
For new applications migrating from the CS4280 to the CS4281, several design considerations need atten-
tion. Joystick coordinate capacitor values should change from 5.6 nF to 12 nF to more closely approximate
legacy game port timing; however, the CS4281 does approximate the CS4280 timing. The CS4281 does
not support ZV-Port found on the 128-pin version of the CS4280. Full PME capabilities are available on
the CS4281 with the support of Vaux and the PME# functions. CLKRUN# only available on the 128-pin
version of the CS4280 is now available on either the 100-pin MQFP or 100-pin TQFP CS4281. The
CS4281 also supports up to two AC ‘97 Codecs that support the Audio Codec Specification 2.1 extensions.
CIRRUS LOGIC PRODUCT DATA SHEET
DS308PP4
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