wm9712l Wolfson Microelectronics plc, wm9712l Datasheet - Page 21

• Manufacturer Part Number: wm9712l
• Description: Ac?97 Audio And Touchpanel Codec
• Manufacturer: Wolfson Microelectronics plc

Production Data
w
RECORD GAIN
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.
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.
Table 8 Record Gain Register
1Ch
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
Mute Audio ADC (both channels)
1: Mute (OFF)
0: No Mute (ON)
Gain range select (left)
0: Standard (0 to 22.5dB, 1.5dB step size)
1: Extended (-17.25 to +30dB, 0.75dB steps)
Record Volume (left)
Standard (GRL=0)
XX0000: 0dB
XX0001: +1.5dB
… (1.5dB steps)
XX1111: +22.5dB
Zero Cross Enable
0: Record Gain changes immediately
1: Record Gain changes when signal is zero
or after time-out
Gain range select (right)
Similar to GRL
Record Volume (right)
Similar to RECVOLL
DESCRIPTION
PD Rev 4.5 August 2006
Extended (GRL=1)
000000: -17.25dB
000001: -16.5dB
… (0.75dB steps)
111111: +30dB
WM9712L
21