Advanced Information

WM8740

WOLFSON MICROELECTRONICS LTD

AI Rev 1.7 July 2000

15

•

ANRES is the reset to the switched capacitor filter.

•

ANMUTE is an analogue muting signal gating the analogue signal at the output (after

the SC filter)

•

AUTOMUTE is asserted when both the IZD register bit is asserted and the input audio

data has been zero on both left and right channels for 1024 input samples. The first

non-zero sample de-asserts.

•

Applying a logic low to MUTEB or setting MUT in Reg2 causes the gain registers to

ramp to zero. When a logic high is applied, the gain ramps slowly back up to the value

held in the appropriate attenuation register (AL or AR). The ramp rate = 128/fs s/0.5dB

step.

If SOFTMUTE is set or

MUTEB=0 then GAINL and

GAINR are overridden to 00

MUTEB

GAINL[0:7]

GAINR[0:7]

ANMUTE

SOFTMUTE

gain ramps between

previous and new gain

setting

Signal

Processing

IZD

ZERO

OPE

FREQ_INVALID

INIT

Automute:

Detect 1024

zero input

samples

Figure 7 Mute Modes