wm8903 Wolfson Microelectronics plc, wm8903 Datasheet - Page 45

• Manufacturer Part Number: wm8903
• Description: Ultra Low Power Codec For Portable Audio Applications
• Manufacturer: Wolfson Microelectronics plc

Pre-Production
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Table 19 DRC Quick-Release Control
GAIN SMOOTHING
The DRC includes a gain smoothing filter in order to prevent gain ripples. A programmable level of
hysteresis is also used to control the DRC gain. This improves the handling of very low frequency
input signals whose period is close to the DRC attack/decay time. DRC Gain Smoothing is enabled
by default and it is recommended to use the default register settings.
The extent of the gain smoothing filter may be adjusted or disabled using the control fields described
in Table 20.
Table 20 DRC Gain Smoothing
R40 (28h)
DRC 0
R41 (29h)
DRC 1
R40 (28h)
DRC 0
REGISTER
REGISTER
ADDRESS
ADDRESS
12:11
BIT
BIT
7:6
5:4
2
3
0
DRC_QR_ENA
DRC_THRESH_
QR [1:0]
DRC_RATE_QR
[1:0]
DRC_THRESH_
HYST [1:0]
DRC_SMOOTH
_ENA
DRC_HYST_EN
A
LABEL
LABEL
DEFAULT
DEFAULT
01
00
1
1
1
01
Quick release enable
0 = disabled
1 = enabled
Quick release crest factor threshold
00 = 12dB
01 = 18dB (default)
10 = 24dB
11 = 30dB
Quick release decay rate
(seconds/6dB)
00 = 0.725ms (default)
01 = 1.45ms
10 = 5.8ms
11 = Reserved
Gain smoothing hysteresis
threshold
00 = Low
01 = Medium (recommended)
10 = High
11 = Reserved
Gain smoothing enable
0 = disabled
1 = enabled
Gain smoothing hysteresis enable
0 = disabled
1 = enabled
PP, Rev 3.1, August 2009
DESCRIPTION
DESCRIPTION
WM8903
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