CS4351
does not encounter a zero crossing. The zero cross function is independently monitored and implemented
for each channel.
Soft Ramp PCM
Soft Ramp allows level changes, both muting and attenuation, to be implemented by incrementally ramp-
ing, in 1/8 dB steps, from the current level to the new level at a rate of 1 dB per 8 left/right clock periods.
Soft Ramp and Zero Cross
Soft Ramp and Zero Cross Enable dictate that signal level changes, either by attenuation changes or mut-
ing, 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 time-out 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.
6.6.2 SOFT VOLUME RAMP-UP AFTER ERROR (RMP_UP) BIT 5
Function:
When set to 1 (default), an un-mute will be performed after executing a filter mode change, after a
LRCK/MCLK ratio change or error, and after changing the Functional Mode. This un-mute 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 un-mute is performed in these instances.
Note: for best results, it is recommended that this feature be used in conjunction with the RMP_DN bit.
6.6.3 SOFT RAMP-DOWN BEFORE FILTER MODE CHANGE (RMP_DN) BIT 4
Function:
When set to 1 (default), a mute will be performed prior to executing a filter mode change. This mute 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 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.
6.6.4 INTERPOLATION FILTER SELECT (FILT_SEL) BIT 2
Function:
When set to 0 (default), the Interpolation Filter has a fast roll off.
When set to 1, the Interpolation Filter has a slow roll off.
The specifications for each filter can be found in the “Combined Interpolation & On-chip Analog Filter Re-
sponse” on page 9, and response plots can be found in figures 15 to 36.
DS566PP2
33
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