WM8725 Wolfson Microelectronics plc, WM8725 Datasheet - Page 10

• Manufacturer Part Number: WM8725
• Description: 99db Stereo Dac
• Manufacturer: Wolfson Microelectronics plc

WM8725
SYSTEM CLOCK
w
The system clock is used to operate the digital filters and the noise shaping circuits. The
system clock input is at pin 14 (SCKI). The frequency of WM8725’s system clock should be
set to 256fs or 384fs, (where fs is the audio sampling frequency). The sample rate is
typically: 32 kHz, 44.1 kHz, 48 kHz or 96kHz.
WM8725 has a system clock detection circuit that automatically determines whether the
system clock being supplied is at 256fs or 384fs. The system clock should be synchronised
with LRCIN, but WM8725 is tolerant of phase differences. Severe distortion in the phase
difference between LRCIN and the system clock will be detected, and cause the device to
automatically resynchronise. During resynchronisation, the output of the device will either
repeat the previous sample, or drop the next sample, depending on the nature of the phase
slip. This will ensure minimal “click“ at the analogue outputs during resynchronisation.
Figure 5 System Clock Timing Requirements
Table 5 System Clock Frequencies Versus Sampling Rate
Notes:
1
Figure 6 Audio Data Input Timing
RATE (LRCIN)
SAMPLING
BCKIN
LRCIN
96kHz sample rate at either 256fs or 384fs are only supported with 5V supplies.
44.1 kHz
32 kHz
48 kHz
96kHz
DIN
SCKI
t
BCH
SYSTEM CLOCK FREQUENCY
11.2896
24.576
12.288
t
256fs
8.192
BCY
1
(MHz)
t
t
BCL
DS
t
SCKIL
16.9340
36.864
12.288
18.432
384fs
t
SCKIH
1
t
t
BL
DH
t
LB
PD Rev 4.1 August 2004
Production Data
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