
ASAHI KASEI
[AK4366]
MS0248-E-01
2004/03
- 11 -
OPERATION OVERVIEW
System Clock
The external clocks required to operate the AK4366 are MCLK(256fs/384fs/512fs), LRCK(fs) and BICK. The master
clock (MCLK) should be synchronized with sampling clock (LRCK). The phase between these clocks does not matter.
The frequency of MCLK is detected automatically, and the internal master clock becomes the appropriate frequency.
Table 1 shows system clock example.
LRCK
MCLK (MHz)
fs
256fs
384fs
8kHz
2.048
3.072
11.025kHz
2.8224
4.2336
12kHz
3.072
4.608
16kHz
4.096
6.144
22.05kHz
5.6448
8.4672
24kHz
6.144
9.216
32kHz
8.192
12.288
44.1kHz
11.2896
16.9344
48kHz
12.288
18.432
Table 1. System Clock Example
In serial mode (P/S pin = “L”), all external clocks (MCLK, BICK and LRCK) should always be present whenever the
DAC is in normal operation mode (PMDAC bit = “1”). If these clocks are not provided, the AK4366 may draw excess
current and will not operate properly because it utilizes these clocks for internal dynamic refresh of registers. If the
external clocks are not present, the DAC should be placed in power-down mode (PMDAC bit = “0”). When MCLK is
input with AC coupling, the MCKAC bit should be set to “1”.
In parallel mode (P/S pin = “H”), all external clocks (MCLK, BICK and LRCK) should always be present whenever the
DAC is in normal operation mode (PDN pin = “H”). If these clocks are not provided, the AK4366 may draw excess
current and will not operate properly because it utilizes these clocks for internal dynamic refresh of registers. If the
external clocks are not present, the DAC should be placed in power-down mode (PDN pin = “L”).
For low sampling rates, DR and S/N degrade because of the outband noise. In serial mode (P/S pin = “L”), DR and S/N
are improved by setting DFS1 bit to “1”. Table 2 shows S/N of HP-amp output. When the DFS1 bit is “1”, MCLK needs
512fs.
Over Sample
Rate
0
0
64fs
8kHz
~
48kHz
256fs/384fs/512fs
0
1
128fs
8kHz
~
24kHz
256fs/384fs/512fs
1
x
256fs
8kHz
~
12kHz
Table 2. Relationship among fs, MCLK frequency and S/N of HP-amp
BICK (MHz)
64fs
0.512
0.7056
0.768
1.024
1.4112
1.536
2.048
2.8224
3.072
512fs
4.096
5.6448
6.144
8.192
11.2896
12.288
16.384
22.5792
24.576
S/N (fs=8kHz, A-weighted)
HP-amp
56dB
75dB
92dB
Default
DFS1
DFS0
fs
MCLK
512fs