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Production Data

WM8987L

PD Rev 4.0 August 2008

ANALOGUE OUTPUTS

ROUT1 OUTPUT

ROUT1 is the non-inverting left-channel output for BTL headsets (see page 54). It can drive 16

Ω or

Ω transducer loads. The ROUT1 signal volume can be adjusted under software control by writing

to ROUT1VOL. Note that gains over 0dB may cause clipping if the signal is large. Any gain setting

below 0101111 (minimum) mutes the output driver. The ROUT1 pin then remains at the same DC

level (the reference voltage on the VREF pin), so that no click noise is produced when muting or un-

muting.

A zero cross detect on the analogue output may also be enabled when changing the gain setting to

minimize audible clicks and zipper noise as the gain updates. A timeout is also available to update

the gain in the case that zero cross detection is enabled but no zero crossing occurs. This function

may be enabled by setting TOEN in register R23 (17h).

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

RO1VU

ROUT1VOL Update

For any change to ROUT1VOL to take

effect, write ‘1’ to this bit.

RO1ZC

Right zero cross enable

1 = Change gain on zero cross only

0 = Change gain immediately

R3 (03h)

ROUT1

Volume

6:0

ROUT1VOL

[6:0]

1111001

ROUT1 Volume

1111111 = +6dB

… (80 steps)

0110000 = -67dB

0101111 to 0000000 = Analogue MUTE

Table 25 ROUT1 Volume Control

LOUT2/ROUT2 OUTPUTS

LOUT2 and ROUT2 are analogue output pins similar to ROUT1. For BTL headsets, LOUT2 is the

non-inverting left output and ROUT2 the inverting right output (with ROUT2INV=1); for single-ended

headsets, LOUT2 is the left output and ROUT2 the right output.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

6:0

LOUT2VOL

[6:0]

1111001

(0dB)

LOUT2 volume

1111111 = +6dB

… (80 steps)

0110000 = -67dB

0101111 to 0000000 = Analogue MUTE

LO2ZC

Left zero cross enable

1 = Change gain on zero cross only

0 = Change gain immediately

R40 (28h)

LOUT2

Volume

LO2VU

LOUT2 Volume Update

0 = Store LOUT2VOL in intermediate

latch (no gain change)

1 = Update gain for both channels

(left=LOUT2VOL, right=from

intermediate latch)

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