WM8961 datasheet(36/116 Pages) WOLFSON

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WM8961

Pre-Production

PP, August 2009, Rev 3.1

DIGITAL TO ANALOGUE CONVERTER (DAC)

Digital data is passed to the WM8961 via the flexible audio interface to the hi-fi DACs. The digital

audio data is converted to over-sampled bit streams in the on-chip, true 24-bit digital interpolation

filters. The bit-stream data enters two multi-bit, sigma-delta DACs, which convert them to high quality

analogue audio signals. The multi-bit DAC architecture reduces high frequency noise and sensitivity to

clock jitter. It also uses a Dynamic Element Matching technique for high linearity and low distortion.

The DACs and digital filters are enabled by the DACL and DACR register bits.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R26 (1Ah)

Power

Management (2)

DACL

Left Channel DAC Enable

0 = DAC disabled

1 = DAC enabled

DACR

Right Channel DAC Enable

0 = DAC disabled

1 = DAC enabled

Table 17 DAC Enable Control

DAC DIGITAL VOLUME CONTROL

The output level (digital volume) of each DAC can be controlled digitally over a range from -71.625dB

to 0dB in 0.375dB steps. The level of attenuation for an eight-bit code X is given by:

0.375

× (X-192) dB for 1 ≤ X ≤ 192;

MUTE for X = 0

0dB for 192

≤ X ≤ 255

The DACVU bit controls the loading of digital volume control data. When DACVU is set to 0, the

LDACVOL or RDACVOL control data will be loaded into the respective control register, but will not

actually change the digital gain setting. Both left and right gain settings are updated when a 1 is

written to DACVU. This makes it possible to update the gain of both channels simultaneously.

See "Volume Updates" section for a description of the volume update function, the zero cross function

and the timeout operation.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R10 (0Ah)

Left Channel

Digital Volume

DACVU

DAC Volume Update

0 = Store LDACVOL in intermediate

latch (no gain change)

1 = Update left and right channel

gains (left = LDACVOL, right =

intermediate latch)

7:0

LDACVOL

[7:0]

11111111

( 0dB )

Left DAC Digital Volume Control

0000 0000 = Digital Mute

0000 0001 = -71.625dB

0000 0010 = -71.250dB

... 0.375dB steps up to

1100 0000 = 0dB

….

1111 1111 = 0dB

(See Table 19 for volume range)

R11 (0Bh)

Right Channel

Digital Volume

DACVU

DAC Volume Update

0 = Store RDACVOL in intermediate

latch (no gain change)

1 = Update left and right channel

gains (left = intermediate latch, right

= RDACVOL)

7:0

RDACVOL

[7:0]

11111111

( 0dB )

Right DAC Digital Volume Control

similar to LDACVOL

(See Table 19 for volume range)

Table 18 Digital Volume Control

Table 19 shows the DAC Digital Volume Range.

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