AK4373 Datasheet, PDF (44/98 Pages) Asahi Kasei Microsystems – Low Power Stereo DAC with HP/SPK-Amp

[AK4373]
■ Digital EQ/HPF/LPF
The AK4373 performs high/low pass filter, stereo separation emphasis, gain compensation, five programmable biquads,
ALC (Automatic Level Control) and digital volume by digital domain for input data (Figure 46). HPF, LPF, FIL3, and EQ
blocks are IIR filters of 1^st order. The filter coefficient of HPF, LPF, FIL3, and EQ blocks can be set to any value.
Refer to the section of “Five Programmable Biquads”, “ALC operation” and “Digital Output Volume” about five
programmable biquads, ALC and digital volume, respectively.
FIL3 coefficient also sets the attenuation of the stereo separation emphasis.
The combination of GN1-0 bit (Table 21) and EQ coefficient set the compensation gain.
FIL3 block becomes HPF when F3AS bits are “0” and become LPF when F3AS bits are “1”.
When EQ, HPF and LPF bits are “0”, EQ, HPF and LPF blocks become “through” (0dB). When each filter coefficient is
changed, each filter should be set to “through”.
HPF
Stereo
Separation
emphasis
LPF
FIL3
Gain compensation
EQ
Gain
Five
Biquads
ALC
DVOL
Any coefficient
F1A13-0
F1B13-0
Any coefficient
F2A13-0
F2B13-0
Any coefficient
F3A13-0
F3B13-0
F3AS
0dB ∼ -10dB
Any coefficient
EQA15-0
EQB13-0
EQC15-0
+12dB ∼ 0dB
GN1-0
+24/+12/0dB
Figure 46. Digital EQ/HPF/LPF (default)
GN1
GN0
Gain
0
0
0dB
(default)
0
1
+12dB
1
x
+24dB
Table 21. Gain select of gain block (x: Don’t care)
MS0991-E-00
- 44 -
2008/09