WM9712CLGEFLSLASHV datasheet(21/78 Pages) WOLFSON

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Production Data

WM9712L

PD, Rev 4.6, November 2011

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.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

1Ch

Record Gain

RMU

Mute Audio ADC (both channels)

1: Mute (OFF)

0: No Mute (ON)

GRL

Gain range select (left)

0: Standard (0 to 22.5dB, 1.5dB step size)

1: Extended (-17.25 to +30dB, 0.75dB steps)

13:8

RECVOLL

000000

Record Volume (left)

Standard (GRL=0)

Extended (GRL=1)

XX0000: 0dB

XX0001: +1.5dB

… (1.5dB steps)

XX1111: +22.5dB

000000: -17.25dB

000001: -16.5dB

… (0.75dB steps)

111111: +30dB

Zero Cross Enable

0: Record Gain changes immediately

1: Record Gain changes when signal is zero

or after time-out

GRR

Gain range select (right)

Similar to GRL

5:0

RECVOLR

000000

Record Volume (right)

Similar to RECVOLL

Table 8 Record Gain Register

WM9712CLGEFL/V Datasheet(PDF) 21 Page - Wolfson Microelectronics plc

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