AK4640_05 Datasheet, PDF (32/78 Pages) Asahi Kasei Microsystems – 16-Bit ΔΣ CODEC with MIC/HP/SPK-AMP

ASAHI KASEI
[AK4640]
„ De-emphasis Filter
The AK4640 includes the digital de-emphasis filter (tc = 50/15µs) by IIR filter. Setting the DEM1-0 bits enables the
de-emphasis filter (Table 16).
DEM1
0
0
1
1
DEM0
Mode
0
44.1kHz
1
OFF
0
48kHz
1
32kHz
Table 16. De-emphasis Control
Default
„ Bass Boost Function
The BST1-0 bits control the amount of low frequency boost applied to the DAC output signal (Table 17) . If the BST1-0
bits are set to “10” (MID Level), use a 47µF capacitor for AC-coupling. If the boosted signal exceeds full scale, the analog
output clips to the full scale. Figure 21 shows the boost frequency response at –20dB signal input.
Boost Frequency (fs=44.1kHz)
0
MAX
-5
-10
MID
-15
-20
MIN
-25
0.01
0.1
1
10
Frequency [kHz]
Figure 21. Boost Frequency (fs=44.1kHz)
BST1
BST0
Mode
0
0
OFF
Default
0
1
MIN
1
0
MID
1
1
MAX
Table 17. Low Frequency Boost Control
MS0273-E-02
- 32 -
2005/04