WM8352 datasheet(66/336 Pages) WOLFSON

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WM8352

Production Data

PD, February 2011, Rev 4.4

13.4.4

CONTROLLING THE PRE-AMPLIFIER GAINS

The gain of each microphone pre-amplifier is controlled by writing to the appropriate control registers.

The gain of each pre-amplifier applies to all three inputs associated with that pre-amplifier, whether

inverting or non-inverting. Although the gain settings for each pre-amplifier are in two separate

registers, both gains can be changed simultaneously using the IN_VU bit (see Table 22).

Additionally, it is also possible to control the gain updates to only occur when the respective signal

crosses through zero. This feature reduces clicking noise caused by gain changes.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R80 (50h)

Left Input

Volume

INL_MUTE

Mute control for left channel input PGA:

0 = Input PGA not muted, normal operation

1 = Input PGA muted (and disconnected from

the following input record mixer).

INL_ZC

Left channel input PGA zero cross enable:

0 = Update gain when gain register changes

1 = Update gain on 1st zero cross after gain

IN_VU

Input left PGA and input right PGA volume do

not update until a 1 is written to either IN_VU

7:2

INL_VOL

[5:0]

01_0000

Left channel input PGA volume

000000 = -12dB

000001 = -11.25dB

010000 = 0dB

111111 = 35.25dB

R81 (51h)

Right Input

Volume

INR_MUTE

Mute control for right channel input PGA:

0 = Input PGA not muted, normal operation

1 = Input PGA muted (and disconnected from

the following input record mixer).

INR_ZC

Right channel input PGA zero cross enable:

0 = Update gain when gain register changes

1 = Update gain on 1st zero cross after gain

IN_VU

Input left PGA and input right PGA volume do

not update until a 1 is written to either IN_VU

7:2

INR_VOL

[5:0]

01_0000

Right channel input PGA volume

000000 = -12dB

000001 = -11.25dB

010000 = 0dB

111111 = 35.25dB

Table 22 Controlling the Microphone Pre-amplifier Gain

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