CS4297 Datasheet, PDF (33/46 Pages) Cirrus Logic – CrystalClear SoundFusion Audio Codec 97

CS4297
CrystalClear™ SoundFusion™ Audio Codec ’97
Vrefout
390 pF ^{to via}
NPO
To +5VA
1 µF
0.1 µF
Y5V
To +5VA
0.1 µF
Y5V
AVss2
AVdd2
AFLT2
AFLT1
AVss1
REFFLT
AVdd1
To Analog
Ground
To Analog
Ground
Analog Ground
DVss1
Pin 1
DVdd1
0.1 µF
Y5V
To +5VD
DVss2
0.1 µF
Y5V
DVdd2
To +5VD
To Digital Ground
Figure 10. Suggested Layout for the CS4297
GROUNDING AND LAYOUT
Figure 10 is the suggested layout for the CS4297.
The decoupling capacitors should be located phys-
ically as close to the pins as possible. Also note the
routing of the REFFLT decoupling capacitors and
the isolation of that ground strip.
It is strongly recommended that the device be locat-
ed on a locally separate analog ground plane. This
analog ground plane is used to keep noise from dig-
ital ground return currents from modulating the
CS4297’s ground potential and degrading perfor-
mance. The digital ground pins should be connect-
ed to the digital ground plane and kept separate
from the analog ground connections of the CS4297
and any other external analog circuitry.
It is also recommended that the common connec-
tion point between the two ground planes (required
to maintain a common ground voltage potential) be
located near the CS4297 just under the digital
ground connections (vias). The AC-Link digital in-
terface connection traces should be routed such that
digital ground plane lies underneath these signals
(on the internal ground layer) from the AC’97 Con-
troller continuously to the CS4297.
DS242F5
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