Function:
The individual channel volume levels are independently controlled by their respective Volume Control
registers when this function is disabled. When enabled, the volume on all channels is determined by
the AOUT1 and AIN1 Volume Control register and the other Volume Control registers are ignored.
7.7.2 SOFT RAMP AND ZERO CROSS CONTROL (ADC_SZC[1:0], DAC_SZC[1:0])
Default = 00
00 - Immediate Change
01 - Zero Cross
10 - Soft Ramp
11 - Soft Ramp on Zero Crossings
Function:
Immediate Change
When Immediate Change is selected all volume level changes will take effect immediately in one step.
Zero Cross
Zero Cross Enable dictates that signal level changes, either by gain changes, attenuation changes or
muting, will occur on a signal zero crossing to minimize audible artifacts. The requested 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 independent-
ly monitored and implemented for each channel.
Soft Ramp
Soft Ramp allows level changes, either by gain changes, attenuation changes or muting, to be imple-
mented by incrementally ramping, 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 on Zero Crossing
Soft Ramp and Zero Cross Enable dictates that signal level changes, either by gain changes, atten-
uation 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.
7.7.3
AUTO-MUTE (AMUTE)
Default = 1
0 - Disabled
1 - Enabled
Function:
The Digital-to-Analog converters of the CS42438 will mute the output following the reception of 8192
consecutive audio samples of static 0 or -1. A single sample of non-static data will release the mute.
Detection and muting is done independently for each channel. The quiescent voltage on the output
will be retained during the mute period. The muting function is affected, similar to volume control
changes, by the Soft and Zero Cross bits (SZC[1:0]).
DS646PP2
47
CIRRUS [ CIRRUS LOGIC ]
