cs42l52 Cirrus Logic, Inc., cs42l52 Datasheet - Page 28

• Manufacturer Part Number: cs42l52
• Description: Low-power, Stereo Codec W/ Headphone & Speaker Amps
• Manufacturer: Cirrus Logic, Inc.

28
4.2.3
Referenced Control Register Location
PGAxVOL[5:0
MAX[2:0], MIN[2:0]
Noise Gate
The noise gate may be used to mute signal levels that fall below a programmable threshold. This prevents
the ALC from applying gain to noise. A programmable delay may be used to set the minimum time before
the noise gate attacks the signal.
Note:
pre-amplifier. For example: If both +32 dB pre-amplification and +12 dB programmable gain is applied,
the maximum attenuation that the noise gate achieves will be 52 dB (-96 + 32 + 12) below full-scale.
Referenced Control
Noise Gate Controls............
changes, the level-controlled output may not always be the same but will always fall within the
thresholds.
b e lo w fu ll s ca le
In p u t (b e fo re A L C )
b e lo w fu ll sc a le
Maximum noise gate attenuation levels will depend on the gain applied in either the PGA or MIC
M IN [2 :0 ]
M IN [2 :0 ]
R e sp o n s e
(a fte r A L C )
O u tp u t
A L C
“PGAx Vol. & ALCx Transition Ctl.: ALC, PGA A (Address 12h) & ALC, PGA B (Address 13h)” on page 55
“ALC Threshold (Address 2Ch)” on page 68
P G A G a in a n d /o r
A tte n u a to r
Register Location
“Noise Gate Control (Address 2Dh)” on page 69
Output
Figure 9. Noise Gate Attenuation
(dB)
-96
R R A T E [5 :0 ]
THRESH[2:0]
Figure 8. ALC
5/13/08
-40
-52 dB
-64 dB
-80 dB
Input (dB)
A R A T E [5 :0
]
M A X [2 :0 ]
b e lo w fu ll s ca le
M A X [2 :0 ]
b e lo w fu ll sca le
CS42L52
DS680F1