WM8956CGEFLSLASHV datasheet(47/80 Pages) WOLFSON

47 / 80 page

Production Data

WM8956

PD, November 2011, Rev 4.1

MASTER MODE DACLRC ENABLE

In master mode, by default DACLRC and BCLK are disabled when the DACs are both disabled.

Figure 31 Master Mode Clock Output Control

COMPANDING

The WM8956 supports A-law and

-law companding. Companding can be enabled on the DAC audio

interface by writing the appropriate value to the DACCOMP register bit.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R9 (09h)

Audio

Interface (2)

4:3

DACCOMP

DAC companding

00 = off

01 = reserved

10 = µ-law

11 = A-law

WL8

0 = off

1 = device operates in 8-bit mode.

Table 29 Companding Control

Companding involves using a piecewise linear approximation of the following equations (as set out by

ITU-T G.711 standard) for data compression:

-law (where =255 for the U.S. and Japan):

F(x) = ln( 1 +

|x|) / ln( 1 + )

-1 ≤ x ≤ 1

A-law (where A=87.6 for Europe):

F(x) = A|x| / ( 1 + lnA)

 for x ≤ 1/A

F(x) = ( 1 + lnA|x|) / (1 + lnA)

 for 1/A ≤ x ≤ 1

The companded data is also inverted as recommended by the G.711 standard (all 8 bits are inverted

for

-law, all even data bits are inverted for A-law). The data will be transmitted as the first 8 MSB’s

of data.

Companding converts 13 bits (

-law) or 12 bits (A-law) to 8 bits using non-linear quantization. The

input data range is separated into 8 levels, allowing low amplitude signals better precision than that of

high amplitude signals. This is to exploit the operation of the human auditory system, where louder

sounds do not require as much resolution as quieter sounds. The companded signal is an 8-bit word

containing sign (1-bit), exponent (3-bits) and mantissa (4-bits).

WM8956CGEFL/V Datasheet(PDF) 47 Page - Wolfson Microelectronics plc

WM8956CGEFL/V Datasheet(HTML) 47 Page - Wolfson Microelectronics plc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80

Datasheet Download

Link URL