WM8956 datasheet(35/80 Pages) WOLFSON

35 / 80 page

Preliminary Technical Data

WM8956

PTD, July 2007, Rev 2.1

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

2:0

ACGAIN

[2:0]

000

(1.0x)

AC Speaker Boost (Boosts speaker AC

output signal by up to 1.8 x on left and

right channels)

000 = 1.00x boost (+0dB)

001 = 1.27x boost (+2.1dB)

010 = 1.40x boost (+2.9dB)

011 = 1.52x boost (+3.6dB)

100 = 1.67x boost (+4.5dB)

101 = 1.8x boost (+5.1dB)

110 to 111 = Reserved

Table 19 SPK_L/SPK_R Volume and Speaker Boost Control

To prevent pop noise, DCGAIN and ACGAIN should not be modified while the speaker outputs are

enabled.

To avoid clipping at speaker ground, ACGAIN should not be greater than DCGAIN.

To avoid clipping at speaker supply, SPKVDD1 and SPKVDD2 must be high enough to support the

peak output voltage when using DCGAIN and ACGAIN functions. The peak output voltage is

AVDD*(DCGAIN+ACGAIN)/2.

DCGAIN should normally be set to the same value as ACGAIN.

See "Volume Updates" for more information on volume update bits, zero cross and timeout

operation.

See "Class D Speaker Outputs" for more information on class D speaker operation.

OUT3 OUTPUT

The OUT3 pin can drive a 16

Ω or 32Ω headphone or a line output or be used as a pseudo-ground for

capless headphone drive (see Headphone Output section). It can also drive out a mono mix of left

and right output mixers (See Output Signal Path).

ENABLING THE OUTPUTS

Each analogue output of the WM8956 can be independently enabled or disabled. The analogue

mixer associated with each output is powered on or off along with the output pin. All outputs are

disabled by default. To save power, unused outputs should remain disabled.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

LOUT1

LOUT1 Output Enable

ROUT1

ROUT1 Output Enable

SPKL

SPK_LP and SPK_LN Volume Control

Enable

SPKR

SPK_RP and SPK_RN Volume Control

Enable

R26 (1Ah)

Power

Management

(2)

OUT3

OUT3 Enable

R49 (31h)

Class D

Control (1)

7:6

SPK_OP_EN

[1:0]

Enable Class D Speaker Outputs

00 = Off

01 = Left speaker only

10 = Right speaker only

11 = Left and right speakers enabled

Note: All “Enable” bits are 1 = ON, 0 = OFF

Table 20 Analogue Output Control

WM8956 Datasheet(PDF) 35 Page - Wolfson Microelectronics plc

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