DS1113F1
43
CS4399
4.9 DSD Interface
The DSD_EN bit, when set, is used to configure the device for processing DSD sources. DSD_PRC_SRC configures the
DSD interface used for feeding into the DSD processor. DSD_SPEED specifies if a 64•Fs or 128•Fs DSD stream is
provided. If PDN_DSDIF = 0 and DSD_M/SB = 1, DSD_SPEED determines the DSDCLK clock frequency generated.
When configuring the DSD interface, follow these steps:
1. Configure the DSD_M/SB, DSD_SPEED, DSD_PRC_SRC, and XSP_3ST.
2. Release PDN_DSDIF.
3. Enable DSD_EN.
The DSD_PM_EN bit selects phase modulation (data plus data inverted) as the style of data input. In this mode, the DSD_
PM_SEL bit selects whether a 128•Fs or 64•Fs clock is used for phase-modulated 64•Fs data (see
). Use of
phase modulation mode may not directly affect the performance of the CS4399, but may lower the sensitivity of other
board-level components to the DSD data signals. Note that phase modulation mode is supported only for DSD 64•Fs data
rate.
The CS4399 can detect overmodulation errors in the DSD data that do not comply to the SACD specification. Setting INV_
DSD_DET enables detection of overmodulation errors. This condition is reported through the DSD_INVAL_A_INT and
DSD_INVAL_B_INT status bits. Overmodulated DSD data is converted as received without intervention, but performance
at these levels cannot be guaranteed. Setting STA_DSD_DET allows the CS4399 to mute a DSD stream that is stuck at
1 or 0. This condition is reported through the DSD_STUCK_INT status bit. See
for descriptions of the DSD
error reporting bits.
More information for these register bits can be found in
.
The DSD input structure and analog outputs are designed to handle a nominal 0 dB-SACD (50% modulation index) at
full-rated performance. When 0 dB-SACD and 0 dBFS PCM need to be level matched, DSD_ZERODB must be set. In this
mode, signals of +3-dB SACD may be applied for brief periods of time; however, performance at these levels is not
guaranteed. If sustained levels appro3-dB SACD levels are required, DSD_ZERODB must be cleared, which
matches a +3-dB SACD output level.
Figure 4-26. DSD Phase Modulation Mode Diagram
DSDA,
DSDB
D1
D0
D2
DSDCLK
DSD Normal Mode
(128•Fs)
D1
D1
D2
D0
DSDCLK
DSDA,
DSDB
(64•Fs)
DSD Phase
Modulation Mode
(64•Fs or
128•Fs)
DSDCLK
= 0)
(
= 0)
(
= 1)