Cirrus Logic CS4245 - Manual (Page 49)

DS656F3 49
CS4245
shown in Table 18 . The volume changes are implemented as dictated by the DACSoft and DACZero-
Cross bits in the DAC Control 2 register (see Section 6.12.1 ).
6.12 DAC Control 2 - Address 0Ch
6.12.1 DAC Soft Ramp or Zero Cross Enable (Bits 7:6)
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 19 .
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 19 .
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 19 .
6.12.2 Invert DAC Output (Bit 5)
Function:
When this bit is set, the output of the DAC is inverted.
Binary Code Volume Setting
00000000 0 dB
00000001 -0.5 dB
00101000 -20 dB
00101001 -20.5 dB
11111110 -127 dB
11111111 -127.5 dB
Table 18. Digital Volume Control Example Settings
7 6 5 4 3 2 1 0
DACSoft DACZero InvertDAC Reserved Reserved Reserved Reserved Active_H/L
DACSoft DACZeroCross 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 19. DAC Soft Cross or Zero Cross Mode Selection