WM8961 datasheet(23/116 Pages) WOLFSON

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WM8961

Pre-Production

PP, August 2009, Rev 3.1

When the Automatic Level Control (ALC) is enabled the input PGA gains are controlled automatically

and the LINVOL and RINVOL bits should not be used.

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

bits.

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. This can be enabled using the LIZC and LIZC

applied. For example, to change the left and right volumes simultaneously, with zero cross enabled,

the sequence would be as detailed in Table 5.

It is recommended to perform a calibration of the DC Servo input channel before using the Input PGA

Zero Cross Detector.

VALUE

COMMENT

R0 (00h) Left Channel

PGA

0bxx1x_xxxx

LIZC = 1: Enable Left Input PGA Zero Cross

Detector

R1 (01h) Right Channel

PGA

0bxx1x_xxxx

RIZC = 1: Enable Right Input PGA Zero Cross

Detector

R0 (00h) Left Channel

PGA

0b001y_yyyy

IPVU = 0; LINMUTE = 0; LIZC = 1; LINVOL

[5:0] = 0by_yyyy: Apply Left Input PGA volume

setting, keep Zero Cross enabled, store update.

R1 (01h) Right Channel

PGA

0b101y_yyyy

IPVU = 1; RINMUTE = 0; RLIZC = 1; RINVOL

[5:0] = 0by_yyyy: Apply Right Input PGA volume

setting, keep Zero Cross enabled, update left and

right channel gains simultaneously.

Table 5 Simultaneous Volume update with Zero Cross

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 CLK_TO_DIV[2:0] Note that SYSCLK must be running to use this function.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R0 (00h)

Left Channel

PGA

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. Requires separate

setting.

1 = Change gain on zero cross

only

0 = Change gain immediately

5:0

LINVOL

[5:0]

011111

( 0dB )

Left Input PGA Volume Control

111111 = +24dB

111110 = +23.25dB

. . 0.75dB steps down to

000000 = -23.25dB

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