WM8987LGECOSLASHV datasheet(30/58 Pages) WOLFSON

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WM8987L

Pre-Production

PP Rev 3.0 January 2007

OUTPUT MIXERS

The WM8987L provides the option to mix the DAC output signal with analogue line-in signals from

the L/RINPUT1/2, RINPUT1/2 pins or a mono differential input (LINPUT1 – RINPUT1 or LINPUT2 –

RINPUT2), selected by DS (see Table 3). The level of the mixed-in signals can be controlled with

PGAs (Programmable Gain Amplifiers).

The mono mixer is designed to allow a number of signal combinations to be mixed, including the

possibility of mixing both the right and left channels together to produce a mono output. To prevent

overloading of the mixer when full-scale DAC left and right signals are input, the mixer inputs from

the DAC outputs each have a fixed gain of -6dB. The bypass path inputs to the mono mixer have

variable gain as determined by R38/R39 bits [6:4].

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R34 (22h)

Left Mixer (1)

2:0

LMIXSEL

000

Left Input Selection for Output Mix

000 = LINPUT1

001 = LINPUT2

011 = Left ADC Input (after PGA /

MICBOOST)

100 = Differential input

Other settings : Reserved

R36 (24h)

Right Mixer

(1)

2:0

RMIXSEL

000

Right Input Selection for Output Mix

000 = RINPUT1

001 = RINPUT2

011 = Right ADC Input (after PGA /

MICBOOST)

100 = Differential input

Other settings : Reserved

Table 21 Output Mixer Signal Selection

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

LD2LO

Left DAC to Left Mixer

0 = Disable (Mute)

1 = Enable Path

LI2LO

LMIXSEL Signal to Left Mixer

0 = Disable (Mute)

1 = Enable Path

R34 (22h)

Left Mixer

Control (1)

6:4

LI2LOVOL

[2:0]

101

(-9dB)

LMIXSEL Signal to Left Mixer Volume

000 = +6dB

… (3dB steps)

111 = -15dB

RD2LO

Right DAC to Left Mixer

0 = Disable (Mute)

1 = Enable Path

RI2LO

RMIXSEL Signal to Left Mixer

0 = Disable (Mute)

1 = Enable Path

R35 (23h)

Left Mixer

Control (2)

6:4

RI2LOVOL

[2:0]

101

(-9dB)

RMIXSEL Signal to Left Mixer Volume

000 = +6dB

… (3dB steps)

111 = -15dB

Table 22 Left Output Mixer Control

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