WM8956 datasheet(21/80 Pages) WOLFSON

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Preliminary Technical Data

WM8956

PTD, July 2007, Rev 2.1

RMP3

Connect RINPUT3 to non-inverting input

of Right Input PGA

0 = RINPUT3 not connected to PGA

1 = RINPUT3 connected to PGA

(Constant input impedance)

RMN1

Connect RINPUT1 to inverting input of

Right Input PGA

0 = RINPUT1 not connected to PGA

1 = RINPUT1 connected to PGA

Table 3 Input PGA Control

INPUT PGA VOLUME CONTROLS

The input PGAs have a gain range from -17.25dB to +30dB in 0.75dB steps. The gains from the

inverting inputs (LINPUT1 and RINPUT1) to the PGA outputs and from the non-inverting inputs

(LINPUT2/RINPUT2 and LINPUT3/RINPUT3) to the PGA output are always common in differential

configuration and controlled by the register bits LINVOL[5:0] and RINVOL[5:0].

The left and right input PGAs can be independently muted using the LINMUTE and RINMUTE

To allow simultaneous volume updates of left and right channels, PGA gains are not altered until a 1

is written to the IPVU bit.

To prevent "zipper noise", a zero-cross function is provided, so that when enabled, volume updates

will not take place until a zero-crossing is detected. In the event of a long period without zero-

crossings, a timeout function is available. When this function is enabled (using the TOEN register

bit), the volume will update automatically after a timeout. The timeout period is set by TOCLKSEL.

Note that an MCLK must be input to the device and SYSCLK running internally to use the timeout

function.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

IPVU

Input PGA Volume Update

0 = Store LINVOL in intermediate

latch (no gain change)

1 = Update left and right channel

gains (left = LINVOL, right =

intermediate latch)

LINMUTE

Left Input PGA Analogue Mute

1 = Enable Mute

0 = Disable Mute

Note: IPVU must be set to un-mute.

LIZC

Left Input PGA Zero Cross Detector

1 = Change gain on zero cross only

0 = Change gain immediately

R0 (00h)

Left Channel

PGA

5:0

LINVOL

[5:0]

010111

( 0dB )

Left Input PGA Volume Control

111111 = +30dB

111110 = +29.25dB

. . 0.75dB steps down to

000000 = -17.25dB

R1 (01h)

Right Channel

PGA

IPVU

Input PGA Volume Update

0 = Store RINVOL in intermediate

latch (no gain change)

1 = Update left and right channel

gains (right = RINVOL, left =

intermediate latch)

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