WM8740

Advanced Information

WOLFSON MICROELECTRONICS LTD

AI Rev 1.7 July 2000

10

DE-EMPHASIS CONTROL

MDDM1

PIN 27

MCDMO

PIN 26

DE-EMPHASIS

LL

Off

L

H

48kHz

H

L

44.1kHz

H

H

32kHz

Table 2 De-Emphasis Control

AUDIO INPUT FORMAT

ML/I2S

PIN 28

CSBIWO

PIN 23

DATA FORMAT

L

L

16 bit normal right

justified

L

H

20 bit normal right

justified

H

L

16 bit I

H

H

24 bit I

Table 3 Audio Input Format

SOFT MUTE

MUTEB

PIN 25

FUNCTION

L

Mute On (no output)

H

Mute Off (normal operation)

Table 4 Soft Mute

A logic low on the MUTEB pin will cause the attenuation to ramp to infinite attenuation at a rate of

128/fs seconds per 0.5dB step. Setting MUTEB high will cause the attenuation to ramp back to its

previous value.

SOFTWARE CONTROL INTERFACE

The WM8740 can be controlled using a 3-wire serial interface. MD/DM0 (pin 26) is used for the

program data, MC/DM1 (pin 22) is used to clock in the program data and ML/I2S (pin 28) is use to

latch in the program data. The 3-wire interface protocol is shown in Figure 6. CSB/IWO (pin 23) must

be low when writing.

ML/I2S (PIN 28)

MC/DM1 (PIN 27)

MD/DM0 (PIN 26)

B15

B14

B13

B2

B1

B0

Figure 6 Three-Wire Serial Interface