WM8990ECS/RV Wolfson Microelectronics, WM8990ECS/RV Datasheet - Page 57

• Manufacturer Part Number: WM8990ECS/RV
• Description: Audio CODECs Stereo CODEC w.Class AB/D speaker driver
• Manufacturer: Wolfson Microelectronics

Specifications of WM8990ECS/RV

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

w
Production Data
HIGH PASS FILTER
A digital high pass filter is applied by default to the ADC path to remove DC offsets. This filter can
also be programmed to remove low frequency noise in voice applications (e.g. wind noise or
mechanical vibration). This filter is controlled using the ADC_HPF_ENA and ADC_HPF_CUT register
bits.
In hi-fi mode the high pass filter is optimised for removing DC offsets without degrading the bass
response and has a cut-off frequency of 3.7Hz at fs=44.1kHz.
In voice mode the high pass filter is optimised for voice communication and it is recommended to
program
ADC_HPF_CUT=10 at fs=16kHz).
Table 17 ADC High Pass Filter Control Registers
Table 18 ADC High Pass Filter Cut-Off Frequencies
The high pass filter characteristics are shown in the "Digital Filter Characteristics" section.
REGISTER
ADDRESS
R14 (0Eh)
Frequency
Sample
11.025
16.000
22.050
24.000
32.000
44.100
48.000
8.000
(kHz)
the
8
6:5
BIT
cut-off
ADC_HPF_CUT
ADC_HPF_ENA
ADC_HPF_CUT
[1:0]
=00
0.7
0.9
1.3
1.9
2.0
2.7
3.7
4.0
frequency
LABEL
below
ADC_HPF_CUT
DEFAULT
1b
00b
Cut-off frequency (Hz)
127
175
190
253
348
379
=01
300Hz
64
88
(e.g.
ADC Digital High Pass Filter Enable
0 = disabled
1 = enabled
ADC Digital High Pass Filter Cut-Off
Frequency (fc)
00 = Hi-fi mode (fc=4Hz at fs=48kHz)
01 = Voice mode 1 (fc=127Hz at fs=16kHz)
10 = Voice mode 2 (fc=130Hz at fs=8kHz)
11 = Voice mode 3 (fc=267Hz at fs=8kHz)
(Note: fc scales with sample rate. See
Table 18 for cut-off frequencies at all
supported sample rates)
ADC_HPF_CUT
ADC_HPF_CUT=11
130
178
258
354
386
514
707
770
=10
DESCRIPTION
PD, March 2009, Rev 4.0
ADC_HPF_CUT
at
1063
1464
1594
267
367
532
733
798
=11
WM8990
fs=8kHz
57
or