AK4687 AKM [Asahi Kasei Microsystems], AK4687 Datasheet - Page 16

• Manufacturer Part Number: AK4687
• Description: Asynchronous Stereo CODEC with Capless Stereo Selector
• Manufacturer: AKM [Asahi Kasei Microsystems]

2. Auto Setting Mode (ACKS bit = “1”)
When the ACKS bit = “1”, DAC is in Auto Setting Mode and the sampling speed is selected automatically by the ratio of
MCLK2/LRCK2, as shown in
When MCLK= 256fs/384fs, the AK4687 supports sampling rate of 32kHz~96kHz
rate is 32kHz~48kHz, DR and S/N will degrade as compared to when MCLK= 512fs/768fs.
■
The DAC of AK4687 includes a digital de-emphasis filter (tc=50/15μs) by IIR filter. Setting the DEM1 bit to “1” enables
the de-emphasis filter. Refer to “FILTER CHARACTERISTICS” about the gain error when this filter is ON. The
de-emphasis filter is OFF in double speed mode (MCLK2= 256fs/38fs ) and quad speed mode (MCLK2=128fs/192fs).
The filter setting is executed in I
MS1307-E-00
De-emphasis Filter
176.4kHz
192.0kHz
32.0kHz
44.1kHz
48.0kHz
32.0kHz
44.1kHz
48.0kHz
88.2kHz
96.0kHz
LRCK
fs
22.5792
24.5760
128fs
Table 13. PORT2(DAC) Sampling Speed (ACKS bit = “1”, Auto Setting Mode)
-
-
-
-
-
512fs, 768fs
256fs, 384fs
128fs, 192fs
33.8688
36.8640
Table 13
MCLK2
192fs
Table 15. MCLK Frequency and DR, S/N (fs = 48kHz)
2
Table 16. De-emphasis Control (Normal Speed Mode)
C control mode and DEM bit controls ON/OFF of the filter.
-
-
-
-
-
and
256fs/384fs
512fs/768fs
11.2896
22.5792
24.5760
12.288
Table 14. System Clock Example
8.192
256fs
Table
MCLK
DEM bit
-
-
-
-
-
1
0
14. In this mode, the settings of DFS1-0 bits are ignored.
Normal Speed Mode
Double Speed Mode
Quad Speed Mode
MCLK (MHz)
16.9344
33.8688
36.8640
12.288
18.432
DAC Sampling Speed (fs) LRCK2
384fs
- 16 -
-
-
-
-
-
De-emphasis Filter
OFF
ON
DR, S/N
16.3840
22.5792
24.5760
102dB
105dB
512fs
-
-
-
-
128kHz~192kHz
32kHz~48kHz
64kHz~96kHz
24.5760
33.8688
36.8640
768fs
(default)
(Table
-
-
-
-
15). But, when the sampling
(Table
36.8640
1152fs
-
-
-
-
-
-
17)
Sampling
Normal
Double
Speed
Quad
[AK4687]
2011/05