Toradex Apalis Series - 2.21 S;PDIF (Sony-Philips Digital Interface I;O)

Apalis Carrier Board Design Guide
Toradex AG l Altsagenstrasse 5 l 6048 Horw l Switzerland l +41 41 500 48 00 l www.toradex.com l info@toradex.com
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It is recommended to place 22R series resistors to the signal lines. Place these resistors close to the
signal outputs
Figure 52: HDA Reference Schematic
2.20.3 Unused Digital Audio Interface Signal Termination
Unused digital audio interface signals can be left unconnected.
2.21 S/PDIF (Sony-Philips Digital Interface I/O)
S/PDIF is a widely used digital interface for multi-channel audio. For consumer audio equipment,
there are two variants of the physical layer available. The first variant uses 75Ω electrical coaxial
cables and RCA connectors. The second variant uses fiber optic cable with TOSLINK connectors.
2.21.1 S/PDIF Signals
Apalis
Pin
Apalis
Signal Name
I/O
Type
Power
Rail
Description
215
SPDIF1_OUT
O
CMOS
3.3V
Serial data output
217
SPDIF1_IN
I
CMOS
3.3V
Serial data input
Table 33: S/PDIF Signals
2.21.2 Reference Schematics
For the fiber optic variant, both the transmitter and receiver is required. There are TOSLINK
connectors available with built-in transmitters and receivers. The coaxial signal is specified as low
voltage signal (max. output 0.6V, min input 0.5V) while the Apalis S/PDIF signals are 3.3V logic
level. Therefore, level shifters are required. The following reference schematic shows a very simple
solution. Some projects may require a galvanically isolated solution
MM70-314-310B1
Apalis - Digital Audio
22 of 25
DAP1_MCLK
194
DAP1_SYNC
204
DAP1_BIT_CLK
200
DAP1_D_OUT
196
DAP1_D_IN
202
DAP1_RESET#
198
X1V
22RRA99B
22RRA99C
22RRA99D
DAP1_D_OUT
DAP1_D_IN
DAP1_SYNC
DAP1_BIT_CLK
DAP1_RESET#
DAP1_3.3V_DV
DAP1_5V_AV
10uF
6.3V
C252
100nF
16V
C251
1uF
16V
C250
GND
GND
DAP1_HDA_SIDESURROUND_R
DAP1_HDA_SIDESURROUND_L
DAP1_HDA_LOW_FREQ
DAP1_HDA_CENTER
DAP1_HDA_MIC2_R
DAP1_HDA_MIC2_VREF
DAP1_HDA_MIC2_L
DAP1_HDA_LINE2_R
DAP1_HDA_LINE2_VREF
DAP1_HDA_LINE2_L
DAP1_HDA_FRONT_R
DAP1_HDA_FRONT_L
DAP1_HDA_LINE1_R
DAP1_HDA_LINE1_VREF
DAP1_HDA_LINE1_L
DAP1_HDA_MIC1_VREF_R
DAP1_HDA_MIC1_R
DAP1_HDA_MIC1_VREF_L
DAP1_HDA_MIC1_L
DAP1_HDA_SURROUND_VREF
DAP1_HDA_SURROUND_L
DAP1_HDA_SURROUND_R
R209
20K
GND
DAP1_HDA_JDREF
DAP1_HDA_SENSE_A
DAP1_HDA_SENSE_B
ALC888-GR
DV_CORE
1
GPIO_0
2
GPIO_1
3
DV_SS
4
SDATA_OUT
5
BIT_CLK
6
DV_SS
7
SDATA_IN
8
DV_DD
9
SYNC
10
RESET#
11
PC_BEEP
12
SENSE_A/SRC_B
13
PORT_E_L
14
PORT_E_R
15
PORT_F_L
16
PORT_F_R
17
CD_L
18
CD_GND
19
CD_R
20
PORT_B_L
21
PORT_B_R
22
PORT_C_L
23
PORT_C_R
24
AV_DD
25
AV_SS
26
VREF_FILT
27
MIC_1_BIAS_L
28
V_REF_C
29
MIC_BIAS_F
30
V_REF_E
31
MIC_1_BIAS_R
32
SENSE_B/SRC_A
34
PORT_D_L
35
PORT_D_R
36
V_REF_A
37
AV_DD
38
PORT_A_L
39
JDREF
40
PORT_A_R
41
AV_SS
42
PORT_G_L
43
PORT_G_R
44
PORT_H_L
45
PORT_H_R
46
S/PDIF_IN/GPIO_1
47
S/PDIF_OUT
48
NC
33
SIDE-R
SIDE-L
LOW FREQU
CENTER
SURR_R
SURR_L
FRONT_L
FRONT_R
LINE1_L
LINE1_R
LINE2_R
LINE2_L
MIC1_L
MIC1_R
MIC2_R
MIC2_L
IC28
AGND2
DAP1_F_HEAD_PRES#
GND
2A
120R@100MHz
L33
10uF
10V
C248
100nF
16V
C247
100nF
16V
C246
2A
120R@100MHz
L32
10uF
10V
C245
100nF
16V
C244
2A
120R@100MHz
L31
10uF
10V
C243
100nF
16V
C239
10uF
10V
C240
100nF
16V
C238
2A
120R@100MHz
L30
4.7uF
10V
+
C241
TIED TOGETHER AT ONE POINT ONLY
3.3V_SW
AGND2
22RRA26A
22RRA26B
10uF
10V
C242
10uF
10V
C249
TP18
DAP1_PC_BEEP
DAP1_CD_L
DAP1_CD_GND
DAP1_CD_R
TP19
TP20
TP33
TP34
DAP1_S/PDIF_IN
10uF10V
C284
GND
5V_SW
DAP1_S/PDIF_OUT
NA
NA NA
NA
NA
0R
R23
NA
DAP1_D_OUT
DAP1_D_IN
DAP1_BIT_CLK
DAP1_SYNC
DAP1_RESET#
TP35
UNDER OR NEAR THE CODEC