WM8994 datasheet(139/359 Pages) WOLFSON

139 / 359 page

Production Data

WM8994

PD, April 2012, Rev 4.4

139

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R35 (0023h)

SPKMIXR

Attenuation

SPKOUT_CLASSAB

Speaker Class AB Mode Enable

0 = Class D mode

1 = Class AB mode

R37 (0025h)

ClassD

5:3

SPKOUTL_BOOST

[2:0]

000

(1.0x)

Left Speaker Gain Boost

000 = 1.00x boost (+0dB)

001 = 1.19x boost (+1.5dB)

010 = 1.41x boost (+3.0dB)

011 = 1.68x boost (+4.5dB)

100 = 2.00x boost (+6.0dB)

101 = 2.37x boost (+7.5dB)

110 = 2.81x boost (+9.0dB)

111 = 3.98x boost (+12.0dB)

2:0

SPKOUTR_BOOST

[2:0]

000

(1.0x)

Right Speaker Gain Boost

000 = 1.00x boost (+0dB)

001 = 1.19x boost (+1.5dB)

010 = 1.41x boost (+3.0dB)

011 = 1.68x boost (+4.5dB)

100 = 2.00x boost (+6.0dB)

101 = 2.37x boost (+7.5dB)

110 = 2.81x boost (+9.0dB)

111 = 3.98x boost (+12.0dB)

R34 (0022h)

SPKMIXL

Attenuation

SPKAB_REF_SEL

Selects Reference for Speaker in

Class AB mode

0 = SPKVDD/2

1 = VMID

R1825

(0721h)

Pull Control

(2)

SPKMODE_PU

SPKMODE Pull-up enable

0 = Disabled

1 = Enabled

Table 74 Speaker Mode and Boost Control

Clocking of the Class D output driver is derived from SYSCLK. The clocking frequency division is

configured automatically, according to the AIFn_SR and AIFnCLK_RATE registers. (See “Clocking

and Sample Rates” for further details of the system clocks and control registers.)

The Class D switching clock is enabled whenever SPKOUTL_ENA or SPKOUTR_ENA is set,

provided also that SPKOUT_CLASSAB = 0. The frequency is as described in Table 75.

When AIF1CLK is selected as the SYSCLK source (SYSCLK_SRC = 0), then the Class D clock

frequency is controlled by the AIF1_SR and AIF1CLK_RATE registers.

When AIF2CLK is selected as the SYSCLK source (SYSCLK_SRC = 1), then the Class D clock

frequency is controlled by the AIF2_SR and AIF2CLK_RATE registers.

Note that the applicable clocks (SYSCLK, AIF1CLK or AIF2CLK) must be present and enabled when

using the speaker outputs in Class D mode.

WM8994 Datasheet(PDF) 139 Page - Wolfson Microelectronics plc

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