CS4239 Datasheet, PDF (78/98 Pages) Cirrus Logic – CrystalClear™ Portable ISA Audio System

CS4239
CrystalClear^TM Portable ISA Audio System
go through to the ground and power plane lay-
ers. Vias and power supply traces should be as
large as possible to minimize the impedance.
POWER SUPPLIES
The power supply providing analog power
should be as clean as possible to minimize cou-
pling into the analog section and degrading
analog performance.
The VD1 is isolated from the rest of the power
supply pins and provide digital power for the
asynchronous parallel ISA bus. The VD1 pin can
be connected directly to the system digital power
supply.
VDF1 through VDF3 provide power to internal
digital sections of the codec and should be qui-
eter than VD1. This can be achieved by using a
ferrite bead to the VD1 supply.
VA provides power to the sensitive analog sec-
tions of the chip and should have a clean,
regulated supply to minimize power supply cou-
pled noise in the analog inputs and outputs.
Digital
Ground
Crystal
Part
Noise
1
Analog
Ground
Digital
Ground
Digital Ground Noise
Digital ^{Ground Noise}
Power
Connector
Figure 23. Suggested Motherboard Layout
78
DS253PP2