CS42L55 Datasheet, PDF (25/73 Pages) Cirrus Logic – Ultra Low Power, Stereo CODEC w/Class H Headphone Amp

Referenced Control
Register Location
PGAxVOL[5:0] ..................... “PGAx Volume” on page 49
ADCxATT[7:0] ...................... “ADCx Volume” on page 50
MAX[2:0], MIN[2:0] .............. “ALC Threshold (Address 26h)” on page 64
Input (before ALC)
MIN[2:0]
below full scale
ALC
Response
PGA Gain and/or
Attenuator
Output
(after ALC)
MIN[2:0]
below full scale
MAX[2:0]
below full scale
MAX[2:0]
below full scale
CS42L55
RRATE[5:0]
ARATE[5:0
]
Figure 11. ALC Operation
4.3 Analog In to Analog Out Passthrough
The CS42L55 accommodates analog routing of the analog input signal directly to the headphone and line
out amplifiers. This feature is useful in applications that utilize an FM tuner where audio recovered over-the-
air must be transmitted to the headphone amplifier without digital conversion in the ADC and DAC. This an-
alog passthrough path reduces power consumption and is immune to modulator switching noise that could
interfere with some tuners. This path is selected using the Line and/or HP mux bits and powering down the
ADC.
Referenced Control
Register Location
PDN_ADCx ......................... “Power Down ADC x” on page 42
HPxMUX.............................. “Headphone Input Select” on page 47
LINExMUX........................... “Line Input Select” on page 47
DS773F1
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