WM8987LGECOSLASHV datasheet(17/58 Pages) WOLFSON

17 / 58 page

Pre-Production

WM8987L

PP Rev 3.0 January 2007

As an example, the WM8987L can be set up to convert one differential and one single ended mono

signal by applying the differential signal to LINPUT1/RINPUT1 and the single ended signal to

RINPUT2. By setting LINSEL to L-R Differential (see Table 4), DS to LINPUT1 - RINPUT1 and

RINSEL to RINPUT2, each mono signal can then be routed to a separate ADC or Bypass pat

The signal inputs are biased internally to the reference voltage VREF. Whenever the line inputs are

muted or the device placed into standby mode, the inputs are kept biased to VREF using special

anti-thump circuitry. This reduces any audible clicks that may otherwise be heard when changing

inputs.

DC MEASUREMENT

For DC measurements (for example, battery voltage monitoring), the input signal at the LINPUT1

and/or RINPUT1 pins can be taken directly into the respective ADC, bypassing both PGA and

microphone boost. The ADC output then becomes unsigned relative to AVDD, instead of being a

signed (two’s complement) number relative to VREF. Setting L/RDCM will override L/RINSEL. The

input range for dc measurement is AGND to AVDD.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

7:6

LINSEL

Left Channel Input Select

00 = LINPUT1

01 = LINPUT2

10 = Reserved

11 = L-R Differential (either LINPUT1-

RINPUT1 or LINPUT2-RINPUT2,

selected by DS)

R32 (20h)

ADC Signal

Path Control

(Left)

5:4

LMICBOOST

Left Channel Microphone Gain Boost

00 = Boost off (bypassed)

01 = 13dB boost

10 = 20dB boost

11 = 29dB boost

7:6

RINSEL

Right Channel Input Select

00 = RINPUT1

01 = RINPUT2

10 = Reserved

11 = L-R Differential (either LINPUT1-

RINPUT1 or LINPUT2-RINPUT2,

selected by DS)

R33 (21h)

ADC Signal

Path Control

(Right)

5:4

RMICBOOST

Right Channel Microphone Gain Boost

00 = Boost off (bypassed)

01 = 13dB boost

10 = 20dB boost

11 = 29dB boost

Table 4 Input Software Control

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

RDCM

Right Channel DC Measurement

0 = Normal Operation, PGA Enabled

1 = Measure DC level on RINPUT1

R31 (1Fh)

ADC input Mode

LDCM

Left Channel DC Measurement

0 = Normal Operation, PGA Enabled

1 = Measure DC level on LINPUT1

Table 5 DC Measurement Select

WM8987LGECO/V Datasheet(PDF) 17 Page - Wolfson Microelectronics plc

WM8987LGECO/V Datasheet(HTML) 17 Page - Wolfson Microelectronics plc

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