WM8976CGEFLSLASHV datasheet(57/114 Pages) WOLFSON

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Production Data

WM8976

PD, Rev 4.5, November 2011

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R54

LOUT2 (SPK)

Volume

control

LOUT2ZC

Speaker volume zero cross enable:

1 = Change gain on zero cross only

0 = Change gain immediately

LOUT2MUTE

Left speaker output mute:

0 = Normal operation

1 = Mute

5:0

LOUT2VOL

111001

Left speaker output volume:

000000 = -57dB

...

111001 = 0dB

...

111111 = +6dB

SPKVU

Not latched

LOUT2 and ROUT2 volumes do not

update until a 1 is written to SPKVU

(in reg 54 or 55)

R55

ROUT2 (SPK)

Volume

control

ROUT2ZC

Speaker volume zero cross enable:

1 = Change gain on zero cross only

0 = Change gain immediately

ROUT2MUTE

Right speaker output mute:

0 = Normal operation

1 = Mute

5:0

ROUT2VOL

111001

Right speaker output volume:

000000 = -57dB

...

111001 = 0dB

...

111111 = +6dB

SPKVU

Not latched

LOUT2 and ROUT2 volumes do not

update until a 1 is written to SPKVU

(in reg 54 or 55)

Table 41 Speaker Volume Control

The signal output on LOUT2/ROUT2 comes from the Left/Right Mixer circuits and can be any

combination of the DAC output, the Bypass path (output of the input boost stage) and the AUX input.

The LOUT2/ROUT2 volume is controlled by the LOUT2VOL/ ROUT2VOL register bits. Gains over

0dB may cause clipping if the signal is large. The LOUT2MUTE/ ROUT2MUTE register bits cause

the speaker outputs to be muted (the output DC level is driven out). The output pins remain at the

same DC level (DCOP), so that no click noise is produced when muting or un-muting.

The speaker output stages also have a selectable gain boost of 1.5x (3.52dB). When this boost is

enabled the output DC level is also level shifted (from AVDD/2 to 1.5xAVDD/2) to prevent the signal

from clipping. A dedicated amplifier BUFDCOP, as shown in Figure 30, is used to perform the DC

level shift operation. This buffer must be enabled using the BUFDCOPEN register bit for this

operating mode. It should also be noted that if SPKVDD is not equal to or greater than 1.5xAVDD this

boost mode may result in signals clipping. Table 43 summarises the effect of the SPKBOOST control

bits.

Note: When boost mode is selected, it is necessary to set LOUT2MUTE (R54[6]) and ROUT2MUTE

(R55[6]) bits for either output to be muted

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