Datasheet

PCM9211
www.ti.com 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 128f
S
, 256f
S
or 512f
S
.
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:
• 512f
S
: 54 kHz and below.
• 256f
S
: 54 kHz to 108 kHz
• 128f
S
: 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 LRCKO PSCK2 PSCK1 PSCK0
128f
S
64f
S
f
S
0 0 0
256f
S
64f
S
f
S
0 1 0
512f
S
(1)
64f
S
f
S
1 0 0
(1) 512f
S
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 (f
S
) 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 BCK SCK (Depends on PSCK[2:0] Setting)
f
S
64f
S
128f
S
256f
S
512f
S
8 kHz 0.512 MHz 1.024MHz 2.048 MHz 4.096 MHz
11.025 kHz 0.7056 MHz 1.4112 MHz 2.8224 MHz 5.6448 MHz
12 kHz 0.768 MHz 1.536 MHz 3.072 MHz 6.144 MHz
16 kHz 1.024 MHz 2.048 MHz 4.096 MHz 8.192 MHz
22.05 kHz 1.4112 MHz 2.8224 MHz 5.6448 MHz 11.2896 MHz
24 kHz 1.536 MHz 3.072 MHz 6.144 MHz 12.288 MHz
32 kHz 2.048 MHz 4.096 MHz 8.192 MHz 16.384 MHz
44.1 kHz 2.8224 MHz 5.6448 MHz 11.2896 MHz 22.5792 MHz
48 kHz 3.072 MHz 6.144 MHz 12.288 MHz 24.576 MHz
64 kHz 4.096 MHz 8.192 MHz 16.384 MHz 32.768 MHz
88.2 kHz 5.6448 MHz 11.2896 MHz 22.5792 MHz 45.1584 MHz
96 kHz 6.144 MHz 12.288 MHz 24.576 MHz 49.152 MHz
128 kHz 8.192 MHz 16.384 MHz 32.768 MHz N/A
176.4 kHz 11.2896 MHz 22.5792 MHz 45.1584 MHz N/A
192 kHz 12.288 MHz 24.576 MHz 49.152 MHz N/A
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