WM8974GEFLSLASHV datasheet(43/87 Pages) WOLFSON

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Production Data

WM8974

PD Rev 4.2 March 2007

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

SPKBOOST

Speaker output boost stage control (see Table

37 for details)

0=No boost (outputs are inverting buffers)

1 = 1.5x gain boost

R49

Output control

MONOBOOST

Mono output boost stage control (see Table 37

for details)

0=No boost (output is inverting buffer)

1=1.5x gain boost

Power

management 1

BUFDCOPEN

Dedicated buffer for DC level shifting output

stages when in 1.5x gain boost configuration.

0=Buffer disabled

1=Buffer enabled (required for 1.5x gain boost)

Table 36 Output Boost Control

SPKBOOST/

MONOBOOST

OUTPUT

STAGE GAIN

OUTPUT DC

LEVEL

OUTPUT STAGE

CONFIGURATION

AVDD/2

Inverting

1.5x

1.5xAVDD/2

Non-inverting

Table 37 Output Boost Stage Details

SPKOUTP/SPKOUTN OUTPUTS

The SPKOUT pins can drive a single bridge tied 8Ω speaker or two headphone loads of 16

Ω or 32Ω

or a line output (see Headphone Output and Line Output sections, respectively). The signal to be

output on SKPKOUT comes from the Speaker Mixer circuit and can be any combination of the DAC

output, the Bypass path (output of the boost stage) and the AUX input. The SPKOUTP/N volume is

controlled by the SPKVOL register bits. Note that gains over 0dB may cause clipping if the signal is

large. The SPKMUTE register bit causes the speaker outputs to be muted (the output DC level is

driven out). The output pins remains at the same DC level (VMIDOP), so that no click noise is

produced when muting or un-muting.

The SPKOUTN pin always drives out an inverted version of the SPKOUTP signal.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

DAC2SPK

Output of DAC to speaker mixer input

0 = not selected

1 = selected

BYP2SPK

Bypass path (output of input boost stage) to

speaker mixer input

0 = not selected

1 = selected

R50

Speaker mixer

control

AUX2SPK

Output of auxiliary amplifier to speaker mixer

input

0 = not selected

1 = selected

R40

Bypass path

attenuation control

SPKATTN

Attenuation control for bypass path (output

of input boost stage) to speaker mixer input

0 = 0dB

1 = -10dB

Table 38 Speaker Mixer Control

WM8974GEFL/V Datasheet(PDF) 43 Page - Wolfson Microelectronics plc

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