[AK4685]
2. Auto Setting Mode (ACKS1/2 bit = “1”)
When the ACKS1(ACKS2) bit = “1”, the DAC is in Auto Setting Mode and the sampling speed is selected automatically
by the ratio of MCLKA/LRCKA or MCLKC/LRCKC, as shown in the Table 8 and Table 9. In this mode, the settings of
DFS21-20 bit or FS11-10 bit are ignored.
MCLKA/C
512fs, 768fs
256fs, 384fs
128fs, 192fs
DAC1/2 Sampling Speed (fs) LRCKA/C
Normal Speed Mode
Double Speed Mode
Quad Speed Mode
32kHz~48kHz
64kHz~96kHz
120kHz~192kHz
(Note: ADC is always in Normal Speed Mode)
Table 8. DAC Sampling Speed (ACKS bit = “1”, Auto Setting Mode)
LRCKA/C
fs
MCLKA/C (MHz)
Sampling
Speed
128fs
192fs
256fs
384fs
512fs
768fs
32.0kHz
44.1kHz
48.0kHz
88.2kHz
96.0kHz
176.4kHz
192.0kHz
-
-
-
-
-
-
-
-
-
-
-
-
-
-
16.3840
22.5792
24.5760
24.5760
33.8688
36.8640
Normal
22.5792
24.5760
33.8688
36.8640
-
-
-
-
-
-
-
-
Double
Quad
-
-
22.5792
24.5760
33.8688
36.8640
-
-
-
-
Table 9. DAC System Clock Example (Auto Setting Mode)
■ De-emphasis Filter
The AK4685 includes a digital de-emphasis filter (tc=50/15μs) by IIR filter. This filter corresponds to three sampling
frequencies (32kHz, 44.1kHz, 48kHz). De-emphasis filter is off in Double speed mode and Quad speed mode. De-
emphasis of each DAC can be set individually by register.
DEM21/DEM11
DEM20/DEM10
Mode
Sampling Speed
Normal Speed
Normal Speed
Normal Speed
Normal Speed
DEM
44.1kHz
OFF
48kHz
32kHz
0
1
2
3
0
0
1
1
0
1
0
1
(default)
Table 10. De-emphasis control
MS1106-E-00
2009/08
- 21 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
