Cirrus Logic CS4265 - Manual (Page 41)

DS657F3 41
CS4265
6.9 ADC Input Control - Address 09h
6.9.1 PGA Soft Ramp or Zero Cross Enable (Bits 4:3)
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 14 .
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 14 .
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 14 .
6.9.2 Analog Input Selection (Bit 0)
Function:
These bits are used to select the input source for the PGA and ADC. Please see Table 15 .
6.10 DAC Channel A Volume Control - Address 0Ah
See 6.11 DAC Channel B Volume Control - Address 0Bh .
7 6 5 4 3 2 1 0
Reserved Reserved Reserved PGASoft PGAZero Reserved Reserved Select
PGASoft PGAZeroCross 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 14. PGA Soft Cross or Zero Cross Mode Selection
Select PGA/ADC Input
0 Microphone-Level Input
1 Line-Level Input
Table 15. Analog Input Selection