CS4270 Datasheet, PDF (37/48 Pages) Cirrus Logic – 24-Bit, 192 kHz Stereo Audio CODEC

8.5 Transition Control - Address 05h
7
DAC Single
Volume
6
soft_dac
5
zc_dac
4
invert
ADC ch B
3
invert
ADC ch A
2
invert
DAC ch B
1
invert
DAC ch A
CS4270
0
De-emph
8.5.1 DAC Single Volume (Bit 7)
Function:
The AOUTA and AOUTB volume levels are independently controlled by the A and the B Channel Volume
Control Bytes when this function is disabled. The volume on both AOUTA and AOUTB are determined by
the A Channel Volume Control Byte (07h) and the B Channel Byte (08h) is ignored when this function is
enabled. Volume and muting functions are affected by the Soft Ramp and ZeroCross functions below.
8.5.2 Soft Ramp or Zero Cross Enable (Bits 6:5)
Function:
Soft Ramp Enable
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.
See Table 12 on page 37.
Zero Cross Enable
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. See Table 9 on page 35.
Soft Ramp and Zero Cross Enable
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 sam-
ple rate) if the signal does not encounter a zero crossing. The zero cross function is independently mon-
itored and implemented for each channel. See Table 9 on page 35.
Soft
ZeroCross
Mode
0
0
Changes to affect immediately
0
1
Zero Cross enabled
1
0
Soft Ramp enabled
1
1
Soft Ramp and Zero Cross enabled
(default)
Table 12. Soft Cross or Zero Cross Mode Selection
8.5.3 Invert Signal Polarity (Bits 4:1)
Function:
When set, this bit activates an inversion of the signal polarity for the appropriate channel. This is useful if
a board layout error has occurred or in other situations where a 180 degree phase shift is desirable.
DS686A1
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