WM8716_06 Datasheet, PDF (9/27 Pages) Wolfson Microelectronics plc – High Performance 24-bit, 192kHz Stereo DAC

Production Data
WM8716
DEVICE DESCRIPTION
The WM8716 is a high performance 128fs oversampling rate stereo DAC employing a novel 64 level
sigma delta DAC design which provides optimised signal-to-noise performance and clock jitter
tolerance. It is ideally suited to high quality audio applications such as CD, DVD-audio, home theatre
receivers and professional mixing consoles. The WM8716 supports sample rates from 8ks/s to
192ks/s.
The control functions of the WM8716 are either pin selected (hardware mode) or programmed via the
serial interface (software mode). Control functions that are available include: data input word length
and format selection (16-24 bits: I²S, left justified or right justified): de-emphasis sample rate
selection (48kHz, 44.1kHz and 32kHz); differential output modes; a software or hardware mute and
independently digitally controllable attenuation on both channels.
The digital filtering may be bypassed entirely by selecting MODE8X. Data is then input directly to the
DAC, bypassing the digital filters. Left and right channels are input separately, using the MODE pin
as the right channel input. This mode allows the use of alternative digital filters, such as the Pacific
Microsonics PMD100 HDCD filter.
SYSTEM CLOCK
In addition to the normal stereo operating mode the WM8716 may also be used in dual differential
mode with either the left or right channel (selectable) being output differentially. Two WM8716s can
then be used in parallel to implement a stereo channel, each supporting a single channel
differentially. This mode is available in both software and hardware modes and may also be used in
conjunction with MODE8X.
Sample rates from 8ks/s up to 96ks/s are available, and automatically selected, with a system clock
of 256fs, 384fs, 512fs or 768fs. In addition a system clock of 128fs or 192fs may be used, with
sample rates up to 192ks/s. With a 128fs or 192fs system clock 64x oversampling mode operation is
automatically selected and the first stage of the digital filter is bypassed.
WM8716 has an asynchronous monitor circuit, which in the event of removal of the master system
clock, resets the digital filters and analogue circuits, muting the output. Re-application of the system
clock re-starts the filters from an intitialised state. Control registers are not reset under this condition.
The WM8716 is tolerant of asynchronous bit clock jitter. The internal signal processing
resynchronises to the external LRCIN once the phase difference between bit clock and the system
clock exceeds half an LRCIN period. During this re-synch period the interpolating filters will either
miss or repeat an audio sample, minimising the audible effects of the operation. Table 1 shows the
typical system clock frequency inputs for the WM8716.
SAMPLING
RATE
(LRCIN)
128fs
SYSTEM CLOCK FREQUENCY (MHZ)
192fs
256fs
384fs
512fs
32kHz
4.096
6.144
8.192
12.288
16.384
44.1kHz
5.6448
8.467
11.2896
16.9340
22.5792
48kHz
6.114
9.216
12.288
18.432
24.576
96kHz
12.288
18.432
24.576
36.864 Unavailable
192kHz
24.576
36.864 Unavailable Unavailable Unavailable
Table 1 System Clock Frequencies Versus Sampling Rate
768fs
24.576
33.8688
36.864
Unavailable
Unavailable
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PD Rev 4.1September 2006
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