AK4633 Datasheet, PDF (42/82 Pages) Asahi Kasei Microsystems – 16-Bit Mono CODEC with ALC & MIC/SPK-AMP

ASAHI KASEI
[AK4633]
When the gain of K is set to “-1”, these Equalizers work as notch filter. If the difference between two center frequencies
of these notch filters is small, the center frequency will differ from the frequency that is calculated by the above equation.
Then, the difference between the actual two center frequencies is smaller that the difference between the two calculated
center frequencies. It is required to adjust the center frequencies when these are calculated. The frequency response can be
confirmed by the control soft that is attached in the demo board kit. If the two center frequencies are near, the actual center
frequencies should be confirmed by this software.
e.g.) Sampling frequency = 44.1kHz, the center frequencies of 2 band notch fitters are 6000Hz and 6500Hz, and the band
width is 200Hz.
When the coefficients that are calculated by fo = 6000Hz and 6500Hz is used, the actual center frequencies are 6017Hz
and 6476Hz. When the coefficients that are calculated by fo = 5984Hz and 6522Hz is used, the actual center frequencies
are 6000Hz and 6500Hz.
Note 29. [changing real number to binary number for the filter coefficient setting upon is as below]
X=( the real filter coefficient setting upon) x 2¹³
Round off the X value to the decimal point and change it to binary number.
The MSB bit of each filter coefficient setting register is a sign bit.
„ Input Digital volume (Manual mode)
When ADCPF bit = “1” and ALC1 bit = “0”, ALC block becomes an input digital volume (manual mode). The digital
volume’s gain is set by IVOL7-0 bits as shown in Table 20. The IVOL7-0 bits value are reflected to this input volume at
zero cross or zero cross time out. The zero crossing timeout period is set by ZTM1-0 bits.
IVOL7-0bits GAIN(0dB)
Step
F1H
+36.0
F0H
+35.625
EFH
+35.25
:
:
0.375dB
92H
+0.375
91H
0.0
90H
-0.375
:
:
2H
-53.625
1H
-54.0
0H
MUTE
Table 20. Input Digital Volume Setting
Default
When writing to the IVOL7-0 bits continually, the control register should be written by an interval more than zero
crossing timeout. If not, zero crossing counter could be reset at each time and volume is not be changed. However, it could
be ignored when writing a same register value as the last time. At this time, zero crossing counter has not been reset, so it
should be written by an interval less than zero crossing timeout.
MS0447-E-03
- 42 -
2006/04