PCM9211
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SBAS495 –JUNE 2010
PLL Clock Source (Built-in PLL and VCO) Details
The PCM9211 an has on-chip PLL (including a voltage-controlled oscillator, or VCO) for recovering the clock
from the S/PDIF input signal.
The VCO-derived clock is identified as the PLL clock source.
When locked, the onboard PLL generates a system clock that synchronizes with the input biphase signal. When
unlocked, the PLL generates its own free-run clock (from the VCO).
The generated system clocks from the PLL can be set to fixed multiples of the input S/PDIF frequency. Register
30h/PSCK[2:0] can configure the output clock to 128fS, 256fS or 512fS.
The PCM9211 also has an automatic default output rate that is calculated based on the incoming S/PDIF
frequency. This calculation and rate are controlled by Register 30h/PSCKAUTO. In its default mode, the SCK
dividing ratio is configured according to these parameters:
•
•
•
512fS: 54 kHz and below.
256fS: 54 kHz to 108 kHz
128fS: 108 kHz and above (or unlocked)
PSCKAUTO takes priority over any settings in PSCK[2:0]. PSCK[2:0] only becomes relevant in the system when
the PSCKAUTO Register is set to '0'.
The PCM9211 can decode S/PDIF input signals between sampling frequencies of 7 kHz and 216 kHz for all
PSCK[2:0] settings. The relationship between the output clock (SCKO, BCKO, LRCKO) at the PLL source and
PSCK[2:0] selection is shown in Table 4.
Table 4. SCKO, BCKO and LRCKO Frequency Set by PSCK[2:0]
OUTPUT CLOCK AT PLL SOURCE
PSCK[2:0] SETTING
SCKO
BCKO
64fS
LRCKO
PSCK2
PSCK1
PSCK0
128fS
256fS
fS
fS
fS
0
0
1
0
1
0
0
0
0
64fS
(1)
512fS
64fS
(1) 512fS SCK is only supported at 108 kHz or lower sampling frequency of incoming biphase signal.
In PLL mode, the output clocks (SCKO, BCKO, LRCKO) are generated from the PLL source clock.
The relationship between the sampling frequencies (fS) of the input S/PDIF signal and the frequency of LRCKO,
BCKO, and SCKO are shown in Table 5.
Table 5. Output Clock Frequency at PLL Lock State
LRCK
fS
BCK
SCK (Depends on PSCK[2:0] Setting)
256fS 512fS
64fS
128fS
8 kHz
0.512 MHz
0.7056 MHz
0.768 MHz
1.024 MHz
1.4112 MHz
1.536 MHz
2.048 MHz
2.8224 MHz
3.072 MHz
4.096 MHz
5.6448 MHz
6.144 MHz
8.192 MHz
11.2896 MHz
12.288 MHz
1.024MHz
2.048 MHz
2.8224 MHz
3.072 MHz
4.096 MHz
5.6448 MHz
6.144 MHz
8.192 MHz
11.2896 MHz
12.288 MHz
16.384 MHz
22.5792 MHz
24.576 MHz
32.768 MHz
45.1584 MHz
49.152 MHz
N/A
11.025 kHz
12 kHz
1.4112 MHz
1.536 MHz
2.048 MHz
2.8224 MHz
3.072 MHz
4.096 MHz
5.6448 MHz
6.144 MHz
8.192 MHz
11.2896 MHz
12.288 MHz
16.384 MHz
22.5792 MHz
24.576 MHz
16 kHz
4.096 MHz
22.05 kHz
24 kHz
5.6448 MHz
6.144 MHz
32 kHz
8.192 MHz
44.1 kHz
48 kHz
11.2896 MHz
12.288 MHz
16.384 MHz
22.5792 MHz
24.576 MHz
32.768 MHz
45.1584 MHz
49.152 MHz
64 kHz
88.2 kHz
96 kHz
128 kHz
176.4 kHz
192 kHz
N/A
N/A
Copyright © 2010, Texas Instruments Incorporated
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