CS42448 datasheet(48/64 Pages) CIRRUS

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DS648F2

CS42448

6.7.2

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 mut-

ing, will occur on a signal zero crossing to minimize audible artifacts. The requested level change will oc-

cur 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.

Soft Ramp

Soft Ramp allows level changes, either by gain changes, attenuation changes or muting, to be implement-

ed 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, 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 inde-

pendently monitored and implemented for each channel.

6.7.3

Auto-Mute (AMUTE)

Default = 1

0 - Disabled

1 - Enabled

Function:

The Digital-to-Analog converters of the CS42448 will mute the output following the reception of 8192 con-

secutive 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

and the MUTEC pin will go active during the mute period. The muting function is affected, similar to vol-

ume control changes, by the Soft and Zero Cross bits (SZC[1:0]).

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