lm49350rl National Semiconductor Corporation, lm49350rl Datasheet - Page 62

• Manufacturer Part Number: lm49350rl
• Description: High Performance Audio Codec Sub-system With A Ground-referenced Stereo Headphone Amplifier & An Ultra Low Emi Class D Loudspeaker Amplifier With Dual I2s/pcm Digital Audio Interfaces
• Manufacturer: National Semiconductor Corporation

www.national.com
Bits
Bits
3:0
3
4
5
6
4
NOISE_FLOOR
SOURCE_OVR
SOURCE_SEL
STEREO LINK
NG_ENB
LIMITER
Field
Field
If set, the circuit will never apply gain to the signal, no matter how small, but it will attenuate the
signal as soon as it reaches target and release it at the decay rate, once signal level reduces below
target. The I
will apply. Care should be taken when choosing the optimum I
the Limiter.
If set, the ALC circuit uses the stereo average of the input signals to control the gain of the stereo
output. This maintains stereo imaging. If this bit is cleared, then both channels operate as dual
mono.
If SOURCE_OVR is set then this manually overides the selection of the input amplifier that is used
to alter the gain for ALC operation.
0 = Both ALCs control AUX gain
1 = Both ALCs control MIC gain
If set, the output of the ALC is not set automatically but is controlled by the SOURCE_SEL bit. If
cleared each ALC controls the input gain of the amplifier (AUX or MIC) that is set to that ADC
channel (or MIC if both are selected).
This sets the anticipated noise floor. Signals lower than the noise floor specified will be gated from
the ALC to avoid noise pumping.
This enables the Noise Gate.
2
C gain setting (at the time the LIMITER is enabled) is the maximum gain that the ALC
TABLE 48. ADC_ALC_2 (0x82h)
NOISE_FLOOR
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
62
Description
Description
2
C gain setting whenever enabling
Noise Floor (dB)
–39
–42
–45
–48
–51
–54
–57
–60
–63
–66
–69
–72
–75
–78
–81
–84