Cirrus Logic CS42L73 - Manual (Page 115)

DS882F1 115
CS42L73
6.43 Noise Gate Control AB (Address 32h)
6.43.1 Noise Gate Enable for Channels A and B (NGx)
Enables noise gating independently for channels A and B if NG_AB = 0b. When enabled, if the particular
channel’s signal amplitude is continuously below the threshold setting (see
“Noise gate Threshold and
Boost for Channels A and B” on page 115 ) for longer than the attack delay (debounce) time (see “Noise
Gate Delay Timing for Channels A and B” on page 115 ), noise gate muting is applied to only that channel.
Noise gate muting is removed (released) without debouncing if the signal level exceeds the threshold.
This bit has no effect if NG_AB = 1b (refer to
“Noise Gate Ganging of Channels A and B” on page 116 ).
Note: Noise gate attack and release rates (soft-ramped as a function of Fs or abrupt) are set according
to the programming of DIGSFT ( “Digital Soft-Ramp” on page 96 ).
6.43.2 Noise gate Threshold and Boost for Channels A and B
THRESHAB sets threshold level (±2 dB) for the A and B channel noise gates. NG_BOOSTAB configures
a +30 dB boost to the threshold setting.
Note: The combined threshold and boost setting defines the signal level where the noise gate begins to
engage. For low settings, the noise gate may not fully engage until the signal level is a few dB
lower.
6.43.3 Noise Gate Delay Timing for Channels A and B
Sets the delay (debounce) time before the noise gate mute attacks.
7 6 5 4 3 2 1 0
NGB NGA NG_BOOSTAB THRESHAB2 THRESHAB1 THRESHAB0 NGDELAYAB1 NGDELAYAB0
NGx Noise Gate Status (NG_AB = 0b)
0 Disable noise gating on channel x
1 Enable noise gating on channel x
THRESHAB[2:0] Minimum Setting (NG_BOOSTAB = 0b) Minimum Setting (NG_BOOSTAB = 1b)
000 -64 dB -34 dB
001 -66 dB -36 dB
010 -70 dB -40 dB
011 -73 dB -43 dB
100 -76 dB -46 dB
101 -82 dB -52 dB
110 Reserved -58 dB
111 Reserved -64 dB
NGDELAYAB[1:0] Delay Setting
00
50 ms
01 100 ms
10 150 ms
11 200 ms