WM8900LGEFK/RV Wolfson Microelectronics, WM8900LGEFK/RV Datasheet - Page 40

• Manufacturer Part Number: WM8900LGEFK/RV
• Description: Audio CODECs Ultra Low Power Hi-Fi CODEC
• Manufacturer: Wolfson Microelectronics

Specifications of WM8900LGEFK/RV

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

WM8900
w
Sample
Frequency
(kHz)
ADC DIGITAL FILTERS
The ADC filters perform true 24-bit signal processing to convert the raw multi-bit oversampled data
from the ADC to the correct sampling frequency to be output on the digital audio interface.
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 the cut-off frequency below 300Hz (e.g. ADC_HPF_CUT=11 at fs=8kHz or
ADC_HPF_CUT=10 at fs=16kHz).
Table 20 ADC High Pass Filter Control Registers
Table 21 ADC High Pass Filter Cut-Off Frequencies
The high pass filter characteristics are shown in the "Digital Filter Characteristics" section.
R14 (0Eh)
ADC
Control
REGISTER
ADDRESS
11.025
16.000
22.050
24.000
32.000
44.100
48.000
8.000
8
6:5
ADC_HPF_CUT
= 00
BIT
ADC_HPF_ENA
ADC_HPF_CUT
[1:0]
0.7
0.9
1.3
1.9
2.0
2.7
3.7
4.0
LABEL
ADC_HPF_CUT
= 01
1
00
DEFAULT
CUT-OFF FREQUENCY (HZ)
127
175
190
253
348
379
64
88
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 21 for cut-off frequencies at all
supported sample rates.)
ADC_HPF_CUT
= 10
130
178
258
354
386
514
707
770
DESCRIPTION
PD, August 2008, Rev 4.0
ADC_HPF_CUT
= 11
Production Data
1063
1464
1594
267
367
532
733
798
40