An external digital host controls the TAS576xM soft mute function by driving the XSMT pin with a specific minimum rise time (tr) and fall time (tf) for soft mute and soft un-mute. The TAS576xM requires tr and tf times of less than 20ns. In the majority of applications, this is no problem, however, traces with high capacitance may have issues.
When the XSMT pin is shifted from high to low (3.3V to 0V), a soft digital attenuation ramp begins. –1dB attenuation is then applied every sample time from 0dBFS to –104dBFS.
When the XSMT pin is shifted from low to high (0V to 3.3V), a soft digital “un-mute” is started. 1dB gain steps are applied every sample time from –104dBFS to 0dBFS.