Production Data
WM8945
REF
1
PARAMETER
DRC_KNEE_IP
DRC_KNEE_OP
DRC_HI_COMP
DRC_LO_COMP
DRC_KNEE2_IP
DRC_NG_EXP
DESCRIPTION
Input level at Knee1 (dB)
Output level at Knee1 (dB)
Compression ratio above Knee1
Compression ratio below Knee1
Input level at Knee2 (dB)
2
3
4
5
Expansion ratio below Knee2
Output level at Knee2 (dB)
6
DRC_KNEE2_OP
7
Table 16 DRC Response Parameters
The noise gate is enabled when the DRC_NG_ENA register is set. When the noise gate is not
enabled, parameters 5, 6, 7 above are ignored, and the DRC_LO_COMP slope applies to all input
signal levels below Knee1.
The DRC_KNEE2_OP knee is enabled when the DRC_KNEE2_OP_ENA register is set. When this
bit is not set, then parameter 7 above is ignored, and the Knee2 position always coincides with the
low end of the DRC_LO_COMP region.
The “Knee1” point in Figure 17 is determined by register fields DRC_KNEE_IP and DRC_KNEE_OP.
Parameter Y0, the output level for a 0dB input, is not specified directly, but can be calculated from the
other parameters, using the equation:
The DRC Compression / Expansion / Limiting parameters are defined in Table 17.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R29 (1Dh)
DRC Noise Gate Enable
0 = Disabled
8
DRC_NG_ENA
0
DRC Control 1
1 = Enabled
R32 (20h)
Input signal level at the Noise Gate
threshold ‘Knee2’.
12:8
DRC_KNEE2_IP
000000
DRC Control 4
00000 = -36dB
00001 = -37.5dB
00010 = -39dB
… (-1.5dB steps)
11110 = -81dB
11111 = -82.5dB
Only applicable when
DRC_NG_ENA = 1.
Input signal level at the Compressor
‘Knee1’.
7:2
DRC_KNEE_IP
000000
000000 = 0dB
000001 = -0.75dB
000010 = -1.5dB
… (-0.75dB steps)
111100 = -45dB
111101 = Reserved
11111X = Reserved
DRC_KNEE2_OP Enable
0 = Disabled
R33 (21h)
13
DRC_KNEE2_OP
_ENA
0
DRC Control 5
1 = Enabled
PD, May 2011, Rev 4.1
39
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
