WM8993 datasheet(91/229 Pages) WOLFSON

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Production Data

WM8993

PD, November 2010, Rev 4.0

ANALOGUE OUTPUTS

The speaker, headphone, earpiece and line outputs are highly configurable and may be used in

many different ways.

SPEAKER OUTPUT CONFIGURATIONS

The speaker outputs SPKOUTL and SPKOUTR can be driven by either of the speaker mixers,

SPKMIXL or SPKMIXR, or by the low power, differential Direct Voice path from IN2LP/VRXN and

IN2RP/VRXP. Fine volume control is available on the speaker mixer paths using the SPKLVOL and

SPKRVOL PGAs. A boost function is available on both the speaker mixer paths and the Direct Voice

path. For information on the speaker mixing options, refer to the “Output Signal Path” section.

The speaker outputs SPKOUTL and SPKOUTR operate in a BTL configuration in Class AB or Class

D amplifier modes. The default mode is class D but class AB mode can be selected by setting the

SPKOUT_CLASSAB_MODE register bit, as defined in Table 60.

The speaker outputs may be configured in two ways:

Stereo Mode – supports up to 1W into stereo 8

Ω BTL loads

Mono Mode – supports up to 2W into a single 4

Ω BTL load

Mono mode is selected by applying a logic high input to the SPKMONO pin (E3). For Stereo mode

this pin should be connected to GND. Note that SPKMONO is referenced to DBVDD.

SPEAKER CONFIGURATION

SPKMONO PIN (E3)

Stereo Mode

GND

Mono Mode

DBVDD

Table 59 SPKMONO Pin Function

For mono operation, the P channels, SPKOUTLP and SPKOUTRP should be connected together on

the PCB, and similarly with the N channels, SPKOUTLN and SPKOUTRN. Refer to External

Components Diagram in the ‘Applications Information’ for more details. In this configuration both left

and right speaker drivers should be enabled (SPKOUTL_ENA=1 and SPKOUTR_ENA=1), but path

selection and volume controls are available on left channel only (SPKMIXL, SPKLVOL and

SPKOUTLBOOST).

Note that for applications with a mono 8

Ω speaker it is possible to improve THD performance at

higher power levels by configuring the output in mono mode instead of running either the left of right

channel in stereo mode.

The connections for stereo and mono speaker configurations are shown in Figure 25.

Figure 25 Mono and Stereo Speaker Output Configuration

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