wm9714l Wolfson Microelectronics plc, wm9714l Datasheet - Page 33

• Manufacturer Part Number: wm9714l
• Description: Ac?97 Audio Codec
• Manufacturer: Wolfson Microelectronics plc

Pre-Production
RECORD GAIN
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The amplitude of the signal that enters the audio ADC is controlled by the Record PGA
(Programmable Gain Amplifier). The PGA gain can be programmed either by writing to the Record
Gain register, or by the Automatic Level Control (ALC) circuit (see next section). When the ALC is
enabled, any writes to the Record Gain register have no effect.
Two different gain ranges can be implemented: the standard gain range defined in the AC’97
standard, or an extended gain range with smaller gain steps. The ALC circuit always uses the
extended gain range, as this has been found to result in better sound quality.
Table 12 Record Gain Register
The output of the Record PGA can also be mixed into the phone and/or headphone outputs (see
“Audio Mixers”). This makes it possible to use the ALC function for the microphone signal in a
smartphone application.
12h
Record Gain
REGISTER
ADDRESS
15
14
13:8
7
6
5:0
BIT
RMU
GRL
RECVOLL
ZC
GRR
RECVOLR
LABEL
1
0
000000
0
0
000000
DEFAULT
Audio ADC Input Mute Control
1 = Mute
0 = No mute
Note: This control applies to both channels
Left ADC PGA Gain Range Control
1 = Extended
0 = Standard
Left ADC Recording Volume Control
Standard (GRL=0)
XX0000: 0dB
XX0001: +1.5dB
… (1.5dB steps)
XX1111: +22.5dB
ADC PGA Zero Cross Control
1 = Zero cross enabled (volume changes
when signal is zero or after time-out)
0 = Zero cross disabled (volume changes
immediately)
Right ADC PGA Gain Range Control
1 = Extended
0 = Standard
Right ADC Recording Volume Control
Standard (GRR=0)
XX0000: 0dB
XX0001: +1.5dB
… (1.5dB steps)
XX1111: +22.5dB
DESCRIPTION
PP, Rev 3.2, October 2008
Extended (GRL=1)
000000: -17.25dB
000001: -16.5dB
… (0.75dB steps)
111111: +30dB
Extended (GRR=1)
000000: -17.25dB
000001: -16.5dB
… (0.75dB steps)
111111: +30dB
WM9714L
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