AK4951AEN Datasheet, PDF (42/105 Pages) Asahi Kasei Microsystems – 24bit Stereo CODEC with MIC/HP/SPK-AMP

[AK4951A]
■ Digital HPF1
A digital High Pass Filter (HPF) is integrated for DC offset cancellation of the ADC input. The cut-off
frequencies (fc) of the HPF1 are set by HPFC1-0 bits. It is proportional to the sampling frequency (fs) and
the default value is 3.7Hz (@fs = 48kHz). HPFAD bit controls the ON/OFF of the HPF1 (HPF ON is
recommended).
HPFC1
bit
0
0
1
1
Table 27. HPF1 Cut-off Frequency
HPFC0
fc
bit
fs=8kHz
fs=16kHz fs=48kHz
0
0.62Hz
1.2Hz
3.7Hz
1
2.47Hz
4.9Hz
14.8Hz
0
19.7Hz
39.5Hz
118.4Hz
1
39.5Hz
78.9Hz
236.8Hz
(default)
■ Microphone Sensitivity Correction
The AK4951A has linear microphone sensitivity correction function controlled by MGL/R7-0 bits.
MGL/R7-0 bits must be set when PMADL/R bits = “0” or PMPFIL bit = “0”.
MGL7-0 bits
MGR7-0 bits
00H
01H
02H
:
7EH
7FH
80H
81H
82H
:
FDH
FEH
FFH
Table 28. Microphone Sensitivity Correction
MG_DATA GAIN (dB)
Calculation
0
Mute
-
1
-42.144
2
-36.124
:
:
126
-0.137
127
-0.068
128
0.000
20 log₁₀(MG_DATA/128) (default)
129
+0.068
130
+0.135
:
:
253
+5.918
254
+5.952
255
+5.987
016001936-E-00
- 42 -
2016/03