WM8980_07 Datasheet, PDF (36/112 Pages) Wolfson Microelectronics plc – Stereo CODEC With Speaker Driver and Video Buffer

WM8980
Pre-Production
SELECTABLE HIGH PASS FILTER
A selectable high pass filter is provided. To disable this filter set HPFEN=0. The filter has two
modes controlled by HPFAPP. In Audio Mode (HPFAPP=0) the filter is first order, with a cut-off
frequency of 3.7Hz. In Application Mode (HPFAPP=1) the filter is second order, with a cut-off
frequency selectable via the HPFCUT register. The cut-off frequencies when HPFAPP=1 are shown
in Table 17.
REGISTER
ADDRESS
R14
ADC Control
BIT
LABEL
8
HPFEN
7
HPFAPP
6:4
HPFCUT
Table 16 ADC Enable Control
DEFAULT
DESCRIPTION
1
High Pass Filter Enable
0=disabled
1=enabled
0
Select audio mode or application mode
0=Audio mode (1^st order, fc = ~3.7Hz)
1=Application mode (2^nd order, fc =
HPFCUT)
000
Application mode cut-off frequency
See Table 17 for details.
HPFCUT
[2:0]
SR=101/100
8 11.025 12
SR=011/010
fs (kHz)
16 22.05 24
SR=001/000
32 44.1 48
000
82
113 122 82 113 122 82 113 122
001
102 141 153 102 141 153 102 141 153
010
131 180 156 131 180 156 131 180 156
011
163 225 245 163 225 245 163 225 245
100
204 281 306 204 281 306 204 281 306
101
261 360 392 261 360 392 261 360 392
110
327 450 490 327 450 490 327 450 490
111
408 563 612 408 563 612 408 563 612
Table 17 High Pass Filter Cut-off Frequencies (HPFAPP=1). Values in Hz.
Note that the High Pass filter values (when HPFAPP=1) are calculated with the assumption that the
SR register bits are set correctly for the actual sample rate as shown in Table 17.
w
PP Rev 3.1 March 2007
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