WM8774IFT datasheet(20/42 Pages) WOLFSON

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WM8774

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PP Rev 1.0 June 2002

The WL[1:0] bits are used to control the input word length.

BIT

LABEL

DEFAULT

DESCRIPTION

10110

Interface Control

5:4

WL[1:0]

Input Word Length

00 : 16 bit data

01: 20 bit data

10: 24 bit data

11: 32 bit data

Note: If 32-bit mode is selected in right justified mode, the WM8774 defaults to 24 bits.

In all modes, the data is signed 2’s complement. The digital filters always input 24-bit data. If the

DAC is programmed to receive 16 or 20 bit data, the WM8774 pads the unused LSBs with zeros. If

the DAC is programmed into 32 bit mode, the 8 LSBs are ignored.

Note: In 24 bit I

2S mode, any width of 24 bits or less is supported provided that ADCLRC/DACLRC is

high for a minimum of 24 BCLKs and low for a minimum of 24 BCLKs.

A number of options are available to control how data from the Digital Audio Interface is applied to

the DAC channels.

Control bit MS selects between audio interface Master and Slave Modes. In Master mode ADCLRC,

DACLRC and BCLK are outputs and are generated by the WM8774. In Slave mode ADCLRC,

DACLRC and BCLK are inputs to WM8774.

BIT

LABEL

DEFAULT

DESCRIPTION

10111

Interface Control

Audio Interface Master/Slave Mode

select:

0 : Slave Mode

1: Master Mode

MASTER MODE ADCLRC/DACLRC FREQUENCY SELECT

In Master mode the WM8774 generates ADCLRC, DACLRC and BCLK. These clocks are derived

from master clock and the ratio of MCLK to ADCLRC and DACLRC are set by ADCRATE and

DACRATE.

BIT

LABEL

DEFAULT

DESCRIPTION

2:0

ADCRATE[2:0]

010

Master Mode MCLK:ADCLRC

ratio select:

010: 256fs

011: 384fs

100: 512fs

101: 768fs

10111 ADCLRC and

DACLRC frequency

select

6:4

DACRATE[2:0]

010

Master Mode MCLK:DACLRC

ratio select:

000: 128fs

001: 192fs

010: 256fs

011: 384fs

100: 512fs

101: 768fs

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