Production Data
WM8912
The slope of the DRC response is determined by register fields DRC_HI_COMP and
DRC_LO_COMP respectively. A slope of 1 indicates constant gain in this region. A slope less than 1
represents compression (i.e. a change in input amplitude produces only a smaller change in output
amplitude). A slope of 0 indicates that the target output amplitude is the same across a range of
input amplitudes; this is infinite compression.
The “knee” in Figure 15 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 parameters are defined in Table 2.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R43 (2Bh)
10:5
DRC_KNEE_IP
[5:0]
00_0000
Input signal at the Compressor
'knee'.
DRC Control 3
000000 = 0dB
000001 = -0.75dB
000010 = -1.5dB
… (-0.75dB steps)
111100 = -45dB
111101 to 111111 = Reserved
4:0
DRC_KNEE_OP
[4:0]
0_0000
Output signal at the Compressor
'knee'.
00000 = 0dB
00001 = -0.75dB
00010 = -1.5dB
… (-0.75dB steps)
11110 = -22.5dB
11111 = Reserved
Compressor slope (upper region)
000 = 1 (no compression)
001 = 1/2
R42 (2Ah)
5:3
DRC_HI_COMP
[2:0]
000
DRC Control 2
010 = 1/4
011 = 1/8
100 = 1/16
101 = 0
110 to 111 = Reserved
Compressor slope (lower region)
000 = 1 (no compression)
001 = 1/2
2:0
DRC_LO_COMP
[2:0]
000
010 = 1/4
011 = 1/8
100 = 0
101 to 111 = Reserved
Table 2 DRC Compression Control
PD, Rev 4.0, September 2010
23
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
