CS4202_05 Datasheet, PDF (44/66 Pages) Cirrus Logic – Audio Codec ’97 with Headphone Amplifier

CS4202
6. SONY/PHILIPS DIGITAL
INTERFACE (S/PDIF)
The S/PDIF digital output is used to interface the
CS4202 to consumer audio equipment external to
the PC. This output provides an interface for stor-
ing digital audio data or playing digital audio data
to digital speakers. Figure 15 illustrates the circuits
necessary for implementing the IEC-958 optical or
consumer interface. For further information on
S/PDIF operation see application note AN22: Over-
view of Digital Audio Interface Data Structures [3].
For further information on S/PDIF recommended
transformers see application note AN134: AES and
S/PDIF Recommended Transformers [4].
7. EXCLUSIVE FUNCTIONS
Some of the digital pins on the CS4202 have mul-
tiplexed functionality. These functions are mutual-
ly exclusive and cannot be requested at the same
time. The following pairs of functions are mutually
exclusive:
• GPIO and Serial Data Port (GPIO0 pin is
shared with LRCLK pin, GPIO1 pin is shared
with SDOUT pin, and GPIO4 pin is shared with
SDO2 pin)
• EAPD and Serial Data Port Serial Clock
(EAPD pin is shared with SCLK pin)
Use of the GPIO0/LRCLK, GPIO1/SDOUT, and
GPIO4/SDO2 pins for serial data port has priority
over their GPIO functionality. There is no priority
assigned to the other exclusive function. A function
currently in use must be disabled or powered down
before the corresponding exclusive function can be
enabled. The following control bits for these func-
tions will behave differently than normal bits: the
EAPD bit in the Powerdown Control/Status Regis-
ter (Index 26h), the GC[4,1:0] bits in the GPIO Pin
Configuration Register (Index 4Ch), and the
SDO2, and SDSC bits in the Serial Port Control
Register (Index 6Ah). These bits can become
read-only bits if they control a feature that is cur-
rently unavailable because the corresponding ex-
clusive feature is already in use, or the
corresponding master control for this feature is not
set.
SPDIF_OUT
R₁
R₂
DVdd 3.3V 5V
R₁ 247.5 Ω 375 Ω
R₂ 107.6 Ω 93.75 Ω
DGND
J1
T₁
+5V_PCI
0.1 µ F
SPDIF_OUT ⁴
3
8.2 kΩ ₂
1
5
DGND
6
DGND
TOTX-173 _DGND
Figure 15. S/PDIF Output
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DS549PP2