WM8959 datasheet(41/155 Pages) WOLFSON

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Pre-Production

WM8959

PP, May 2008, Rev 3.1

INPUT PGA VOLUME CONTROL

Each of the four Input PGAs has an independently controlled gain range of -16.5dB to +30dB in

1.5dB steps. The gains on the inverting and non-inverting inputs to the PGAs are always equal. Each

Input PGA can be independently muted using the PGA mute bits as described in Table 5, with

specified mute attenuation achieved by simultaneously disconnecting the corresponding inputs

described in Table 4.

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 TOCLK_ENA

timeout period is set by TOCLK_RATE. See “Clocking and Sample Rates” for more information on

these fields.

The IPVU bit controls the loading of the input PGA volume data. When IPVU is set to 0, the PGA

volume data will be loaded into the respective control register, but will not actually change the gain

setting. The LIN12, RIN12, LIN34, RIN34 volume settings are all updated when a 1 is written to

IPVU. This makes it possible to update the gain of all input paths simultaneously.

The Input PGA Volume Control register fields are described in Table 5 and Table 6.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

IPVU[0]

N/A

Input PGA Volume Update

Writing a 1 to this bit will cause all input

PGA volumes to be updated

simultaneously (LIN12, LIN34, RIN12 and

RIN34)

LI12MUTE

LIN12 PGA Mute

0 = Disable Mute

1 = Enable Mute

LI12ZC

LIN12 PGA Zero Cross Detector

0 = Change gain immediately

1 = Change gain on zero cross only

R24 (18h)

4:0

LIN12VOL

[4:0]

01011b

(0dB)

LIN12 Volume

(See Table 6 for volume range)

IPVU[1]

N/A

Input PGA Volume Update

Writing a 1 to this bit will cause all input

PGA volumes to be updated

simultaneously (LIN12, LIN34, RIN12 and

RIN34)

LI34MUTE

LIN34 PGA Mute

0 = Disable Mute

1 = Enable Mute

LI34ZC

LIN34 PGA Zero Cross Detector

0 = Change gain immediately

1 = Change gain on zero cross only

R25 (19h)

4:0

LIN34VOL

[4:0]

01011b

(0dB)

LIN34 Volume

(See Table 6 for volume range)

IPVU[2]

N/A

Input PGA Volume Update

Writing a 1 to this bit will cause all input

PGA volumes to be updated

simultaneously (LIN12, LIN34, RIN12 and

RIN34)

RI12MUTE

RIN12 PGA Mute

0 = Disable Mute

1 = Enable Mute

R26 (1Ah)

RI12ZC

RIN12 PGA Zero Cross Detector

0 = Change gain immediately

1 = Change gain on zero cross only

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