WM9090ECSSLASHR datasheet(28/81 Pages) WOLFSON

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WM9090

Production Data

PD, November 2010, Rev 4.1

When the AGC applies signal attenuation triggered by the anti-clip threshold, the signal gain is

reduced at a rate that is set by the AGC_CLIP_ATK register. When the anti-clip threshold is no

longer met (due to the signal level reduction), then the AGC increases the signal gain at a rate set by

the AGC_CLIP_DCY register.

Note that, when the anti-clip and power limiting thresholds are both triggered concurrently, then the

signal gain is reduced at the rate set by the AGC_CLIP_ATK register and is increased at the rate set

by AGC_PWR_DCY. These fields are defined in Table 13 and Table 14 respectively.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R98 (62h)

AGC Control

AGC_CLIP_ENA

Enable AGC Anti-Clip Mode

0 = Disabled

1 = Enabled

11:8

AGC_CLIP_THR [3:0]

0110

AGC Anti-Clip Threshold

Sets the headroom between

SPKPGA output and SPKVDD at

which Anti-Clip limiting will be

applied

0000 = -200mV

0001 = -150mV

0010 = -100mV

0011 = -50mV

0100 = 0mV

0101 = 50mV

0110 = 100mV

0111 = 150mV

1000 = 200mV

1001 = 250mV

1010 = 300mV

1011 = 400mV

1100 = 500mV

1101 = 600mV

1110 = 700mV

1111 = 800mV

6:4

AGC_CLIP_ATK [2:0]

100

AGC Anti-Clip Attack Rate

Sets the rate of AGC gain reduction

when clipping is detected

000 = 0.6ms/6dB

001 = 5.4ms/6dB

010 = 10.2ms/6dB

011 = 15.0ms/6dB

100 = 19.8ms/6dB

101 = 24.6ms/6dB

110 = 29.4ms/6dB

111 = 34.1ms/6dB

2:0

AGC_CLIP_DCY [2:0]

000

AGC Anti-Clip Decay Rate

Sets the rate of AGC gain

increments after a period of clipping

000 = 120ms/6dB

001 = 480ms/6dB

010 = 820ms/6dB

011 = 1170ms/6dB

100 = 1640ms/6dB

101 = 2050ms/6dB

110 = 2730ms/6dB

111 = 4100ms/6dB

Table 13 AGC Anti-Clip Control

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