WM8976 Wolfson Microelectronics Ltd., WM8976 Datasheet - Page 26

• Manufacturer Part Number: WM8976
• Description: The WM8976 is a low power, high quality stereo codec designed for portable applications such as Digital still camera or Digital Camcorde
• Manufacturer: Wolfson Microelectronics Ltd.

WM8976
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Table 12 ADC Control
SELECTABLE HIGH PASS FILTER
Table 13 ADC Enable Control
Table 14 High Pass Filter Cut-off Frequencies (HPFAPP=1). Values in Hz.
The polarity of the output signal can also be changed under software control using the ADCLPOL
register bit.
With ADCOSR=0 the oversample rate is 64x which gives lowest power operation and when
ADCOSR=1 the oversample rate is 128x which gives best performance.
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 14.
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 14.
HPFCUT
[2:0]
000
001
010
011
100
101
110
111
R14
ADC Control
R14
ADC Control
REGISTER
ADDRESS
REGISTER
ADDRESS
The oversampling rate of the ADC can be adjusted using the ADCOSR register bit.
102
131
163
204
261
327
408
82
8
8
7
6:4
SR=101/100
BIT
0
3
BIT
11.025
113
141
180
225
281
360
450
563
ADCLPOL
ADCOSR
HPFEN
HPFAPP
HPFCUT
LABEL
LABEL
122
153
156
245
306
392
490
612
12
102
131
163
204
261
327
408
16
82
1
0
000
DEFAULT
SR=011/010
0
0
DEFAULT
fs (kHz)
22.05
113
141
180
225
281
360
450
563
High Pass Filter Enable
0=disabled
1=enabled
Select audio mode or application mode
0=Audio mode (1
1=Application mode (2
HPFCUT)
Application mode cut-off frequency
See Table 14 for details.
122
153
156
245
306
392
490
612
24
ADC polarity adjust:
0=normal
1=inverted
0=64x (lower power)
1=128x (best performance)
ADC oversample rate select:
102
131
163
204
261
327
408
32
82
DESCRIPTION
DESCRIPTION
SR=001/000
st
44.1
113
141
180
225
281
360
450
563
order, fc = ~3.7Hz)
PP Rev 3.0 April 2006
nd
order, fc =
Pre-Production
122
153
156
245
306
392
490
612
48
26