[AK4493]
017012230-E-00
2017/12
- 39 -
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System Clock
[1] PCM Mode
The external clocks, which are required to operate the AK4493, are MCLK, BICK and LRCK. MCLK, BICK
and LRCK should be synchronized but the phase of MCLK is not critical. MCLK is used to operate the
digital interpolation filter, the delta sigma modulator and SCF.
There are Manual Setting Mode and Auto Setting Mode (fs auto detection) for MCLK frequency setting
(
). In Manual Setting Mode (ACKS pin =
“L” or ACKS bit = “0”), MCLK frequency is set
automatically but the sampling speed (LRCK frequency) is set by DFS[2:0] bits (
). The sampling
frequency is fixed to Normal Speed Mode in Pin Control Mode (PSN pin =
“H”), and it is set by DFS[2:0]
bits in Register Control Mode (PSN pin =
“L”). In Register Control Mode, the AK4493 is in Manual Setting
Mode when power-down is released (PDN pin =
“L” → “H”).
In Auto Setting Mode
(ACKS pin = “H” or ACKS bit = “1”), sampling speed and MCLK frequency are
detected automatically (
) and then the initial master clock is set to the appropriate
frequency (
All circuits except control registers, bias generation circuit and internal LDO (if LDOE pin =
“H”) of the
AK4493 are automatically placed in power-down state when MCLK is stopped for more than 1us during
normal operation (PDN pin =
“H”), and the analog output becomes Hi-z state. When MCLK is input again,
the AK4493 exits this power-down state and starts operation again. In this case, register settings are not
initialized. The AK4493 is in power-down mode until MCLK, BICK and LRCK are supplied and the analog
output is floating state.
Table 5. System Clock Setting Mode
ACKS bit (pin)
Mode
0 (L)
Manual Setting Mode
(register default)
1 (H)
Auto Setting Mode
(1) Pin Control Mode
(PSN pin = “H”)
1-
1. Manual Setting Mode (ACKS pin = “L”)
The MCLK frequency corresponding to each sampling speed should be provided externally (
The sampling frequency is fixed to Normal Speed Mode in Pin Control Mode. In this mode, Hex, Octal,
Quad and Double Speed Modes are not available.
Table 6. System Clock Example (Manual Setting Mode in Pin Control Mode) (N/A: Not Available)
LRCK
MCLK (MHz)
BICK
fs
128fs
192fs
256fs
384fs
512fs
768fs
1152fs
64fs
32.0kHz
N/A
N/A
8.1920
12.2880
16.3840
24.5760
36.8640 2.0480MHz
44.1kHz
N/A
N/A
11.2896
16.9344
22.5792
33.8688
N/A
2.8224MHz
48.0kHz
N/A
N/A
12.2880
18.4320
24.5760
36.8640
N/A
3.0720MHz