Cirrus Logic CS4398 - Manual (Page 35)

DS568F1 35
CS4398
7.7 Ramp and Filter Control - Register 07h
7.7.1 Soft Ramp AND Zero Cross CONTROL (SZC1:0) Bits 7-6
Default = 10
Function:
Immediate Change
When Immediate Change is selected, all level changes will take effect immediately in one step.
Zero Cross
Zero Cross Enable dictates that signal-level changes, either by attenuation changes or muting, will occur
on a signal zero crossing to minimize audible artifacts. The requested 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.
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 DSD
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 512 DSD_SCLK periods
(1024 periods if 128x DSD_SCLK is used).
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.
7 6 5 4 3 2 1 0
SZC1 SZC0 RMP_UP RMP_DN Reserved FILT_SEL Reserved DIR_DSD
1 0 1 1 0 0 0 0
SZC1 SZC0 PCM Description DSD Description
0 0 Immediate Change Immediate Change
0 1 Zero Cross
1 0 Soft Ramp Soft Ramp
1 1 Soft Ramp on Zero Crossings