Cirrus Logic CS42L51 - Manual (Page 59)

DS679F1 59
CS42L51
DAC Soft Ramp and Zero Cross Control (DAC_SZC[1:0])
Default = 10
00 - Immediate Change
01 - Zero Cross
10 - Soft Ramp
11 - Soft Ramp on Zero Crossings
Function:
Note: The DATA_SEL[1:0] bits in reg09h must be set to ‘01’b to enable function control
Immediate Change
When Immediate Change is selected all volume-level changes will take effect immediately in one step.
Zero Cross
This setting 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 1024 and 2048 sample periods (21.3 ms to 42.7 ms at 48 kHz sample rate) if the
signal does not encounter a zero crossing. The zero cross function is independently monitored and imple-
mented for each channel.
Note: The LIM_SRDIS bit is ignored.
Soft Ramp
Soft Ramp allows level changes, either by gain changes, attenuation changes or muting, to be implemented
by incrementally ramping, in 1/8 dB steps, from the current level to the new level at a rate of 0.5 dB per 4
left/right clock periods.
Soft Ramp on Zero Crossing
This setting 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 independently monitored and im-
plemented for each channel.
Note: The LIM_SRDIS bit is ignored.
6.10 ALCX & PGAX Control: ALCA, PGAA (Address 0Ah) & ALCB, PGAB (Address 0Bh)
ALCX Soft Ramp Disable (ALCX_SRDIS)
Default: 0
0 - Off
1 - On
Function:
Overrides the SOFTx bit setting for the ADC. When this bit is set, the ALC attack rate in the PGA will not be
dictated by the soft ramp setting. ALC volume-level changes will take effect in one step.
7 6 5 4 3 2 1 0
ALCX_SRDIS ALCX_ZCDIS Reserved PGAX_VOL4 PGAX_VOL3 PGAX_VOL2 PGAX_VOL1 PGAX_VOL0