Cirrus Logic CS4385A - Manual (Page 43)

DS837F2 43
CS4385A
Soft Ramp on Zero Crossing
Soft Ramp and Zero Cross Enable dictates that signal-level changes, either by attenuation changes or
muting, will occur in 1/8 dB steps and be implemented on a signal zero crossing. The 1/8 dB level change
will occur after a timeout period between 512 and 1024 sample periods (10.7 ms to 21.3 ms at 48 kHz
sample rate) if the signal does not encounter a zero crossing. The zero cross function is independently
monitored and implemented for each channel.
7.8.2 Soft Volume Ramp-Up After Error (RMP_UP)
Function:
An un-mute will be performed after executing an LRCK/MCLK ratio change or error and after changing
the Functional Mode.
When set to 1 (default), this unmute is affected, similar to attenuation changes, by the Soft and Zero Cross
bits in the Volume and Mixing Control register.
When set to 0, an immediate unmute is performed in these instances.
Note: For best results, it is recommended that this feature be used in conjunction with the RMP_DN bit.
7.8.3 Soft Ramp-Down Before Filter Mode Change (RMP_DN)
Function:
If either the FILT_SEL or DEM bits are changed, the DAC will stop conversion for a period of time to
change its filter values. This bit selects how the data is affected prior to and after the change of the filter
values.
When set to 1 (default), a mute will be performed prior to executing a filter mode change and an un-mute
will be performed after executing the filter mode change. This mute and un-mute are affected, similar to
attenuation changes, by the Soft and Zero Cross bits in the Volume and Mixing Control register.
When set to 0, an immediate mute is performed prior to executing a filter mode change.
Note: For best results, it is recommended that this feature be used in conjunction with the RMP_UP bit.
7.8.4 PCM Auto-Mute (PAMUTE)
Function:
When set to 1 (default), the Digital-to-Analog converter output will mute following the reception of 8192
consecutive audio samples of static 0 or -1. A single sample of non-static data will release the mute. De-
tection and muting is done independently for each channel. The quiescent voltage on the output will be
retained, and the Mute Control pin will go active during the mute period.
When set to 0, this function is disabled.
7.8.5 DSD Auto-Mute (DAMUTE)
Function:
When set to 1 (default), the Digital-to-Analog converter output will mute following the reception of 256 re-
peated 8-bit DSD mute patterns (as defined in the SACD specification).
A single bit not fitting the repeated mute pattern (mentioned above) will release the mute. Detection and
muting is done independently for each channel. The quiescent voltage on the output will be retained, and
the Mute Control pin will go active during the mute period.