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WM8777
The PLL performs best when f2 is around 90MHz. Its stability peaks at N=8. Some example settings are shown below.
XTALC
LK
DESIRED
OUTPUT
(MHz)
F2
PRE
POST
SCALE
R
N
K
(MHz)
SCALE
(Hex)
(Hex)
(MHz)
(F1)
11.91
11.91
12
11.2896
12.288
11.2896
12.288
11.2896
12.288
11.2896
12.288
11.2896
12.288
11.2896
12.288
11.2896
12.288
11.2896
12.288
11.2896
12.288
11.2896
12.288
90.3168
98.304
90.3168
98.304
90.3168
98.304
90.3168
98.304
90.3168
98.304
90.3168
98.304
90.3168
98.304
90.3168
98.304
90.3168
98.304
90.3168
98.304
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
7.5833
8.2539
7.5264
8.192
7
8
7
8
6
7
6
6
9
A
9
9
9
9
7
8
6
7
6
7
25545C
103FF6
21B089
C49BA
3CA2F4
23F548
116872
34E818
1A1CAC
F5C28
12
13
6.9474
7.5618
6.272
13
14.4
14.4
19.2
19.2
19.68
19.68
19.8
19.8
24
6.8267
9.408
10.24
9.1785
9.9902
9.1229
9.9297
7.5264
8.192
B6D22
3F6017
7DDCA
3B8023
21B089
C49BA
3CA2F4
23F548
2C2B30
12089E
24
26
6.9474
7.5618
6.6901
7.2818
26
27
27
Table 32 PLL Frequency Examples
S/PDIF TRANSCEIVER FEATURES
•
•
•
•
•
•
•
•
IEC-60958 compatible with 32 to 96k frames/s support
Support for Rx and Tx of S/PDIF data
Clock synthesis PLL with reference clock input and low jitter output
Input mux with support for up to 4 S/PDIF inputs
Register controlled Channel Status bit configuration
Register read-back of recovered Channel Status bits and error flags
Detection of non-audio data, sample rate, de-emphasis
Programmable GPO for error flags and frame status flags
An IEC-60958 compatible S/PDIF transceiver is integrated into the WM8777. Operation of the
S/PDIF function may be synchronous or asynchronous to the rest of the digital audio circuits.
The receiver performs data and clock recovery, and sends recovered data either off the chip to an
external DSP (via Primary or Secondary Audio Interfaces), or if the data is audio PCM, it can route
the stereo recovered data to DAC1. The recovered clock may be routed out of the chip onto a pin for
external use, and may be used to clock the internal DAC and ADC circuits as required.
The transmitter generates S/PDIF frames where audio data may be sourced from the ADC, S/PDIF
Receiver, Primary or Secondary Audio Interfaces.
PP Rev 1.94 November 2004
45
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
