WM8912
Production Data
GAIN LIMITS
The minimum and maximum gain applied by the DRC is set by register fields DRC_MINGAIN and
DRC_MAXGAIN. These limits can be used to alter the DRC response from that illustrated in Figure
15. If the range between maximum and minimum gain is reduced, then the extent of the dynamic
range control is reduced. The maximum gain prevents quiet signals (or silence) from being
excessively amplified.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R41 (29h)
3:2
DRC_MINGAIN [1:0]
10
Minimum gain the DRC can use
to attenuate audio signals
DRC Control 1
00 = 0dB (default)
01 = -6dB
10 = -12dB
11 = -18dB
1:0
DRC_MAXGAIN
[1:0]
00
Maximum gain the DRC can use
to boost audio signals
00 = 12dB
01 = 18dB (default)
10 = 24dB
11 = 36dB
Table 3 DRC Gain Limits
DYNAMIC CHARACTERISTICS
The dynamic behaviour determines how quickly the DRC responds to changing signal levels. Note
that the DRC responds to the average (RMS) signal amplitude over a period of time.
DRC_ATK determines how quickly the DRC gain decreases when the signal amplitude is high.
DRC_DCY determines how quickly the DRC gain increases when the signal amplitude is low.
These register fields are described in Table 4. Note that the register defaults are suitable for general
purpose microphone use.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R41 (29h)
15:12
DRC_ATK [3:0]
0011
Gain attack rate (seconds/6dB)
DRC Control 1
0000 = Reserved
0001 = 182μs
0010 = 363μs
0011 = 726μs (default)
0100 = 1.45ms
0101 = 2.9ms
0110 = 5.8ms
0111 = 11.6ms
1000 = 23.2ms
1001 = 46.4ms
1010 = 92.8ms
1011-1111 = Reserved
PD, Rev 4.0, September 2010
24
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