ASAHI KASEI
[AK4702EQ]
OPERATION OVERVIEW
System Clock
The external clocks required to operate the DAC section of AK4702 are MCLK, LRCK and BICK. The master clock
(MCLK) corresponds to 256fs or 384fs. MCLK frequency is automatically detected, and the internal master clock
becomes 256fs. The MCLK should be synchronized with LRCK but the phase is not critical. Table 1 illustrates
corresponding clock frequencies. All external clocks (MCLK, BICK and LRCK) should always be present whenever the
DAC section of AK4702 is in the normal operating mode (STBY bit = “0”). If these clocks are not provided, the AK4702
may draw excess current because the device utilizes dynamically refreshed logic internally. The DAC section of AK4702
should be reset by STBY = “0” after threse clocks are provided. If the external clocks are not present, place the AK4702
in power-down mode (STBY bit = “1”). After exiting reset at power-up etc., the AK4702 remains in power-down mode
until MCLK and LRCK are input.
LRCK
fs
MCLK
BICK
64fs
256fs
384fs
32.0kHz
44.1kHz
48.0kHz
8.1920MHz
11.2896MHz
12.2880MHz
12.2880MHz
16.9344MHz
18.4320MHz
2.0480MHz
2.8224MHz
3.0720MHz
Table 1. System clock example
Audio Serial Interface Format
Data is shifted in via the SDTI pin using BICK and LRCK inputs. The DIF0 and DIF1 bits can select four formats in serial
mode as shown in Table 2. In all modes, the serial data is MSB-first, 2’s compliment format and is latched on the rising
edge of BICK. Mode 2 can also be used for 16 MSB justified formats by zeroing the unused two LSBs.
Mode DIF1 DIF0 SDTI Format
BICK
≥32fs
≥36fs
≥36fs
≥36fs or
32fs
Figure
Figure 3
Figure 3
Figure 4
0
1
2
0
0
1
0
1
0
16bit LSB Justified
18bit LSB Justified
18bit MSB Justified
3
1
1
18bit I2S Compatible
Figure 5
Default
Table 2. Audio Data Formats
LRCK
BICK
SDTI
Mode 0
Don’t care
14
0
0
Don’t care
Don’t care
14
15
0
0
15
15:MSB, 0:LSB
SDTI
Mode 1
Don’t care
17 16 15 14
17 16 15 14
17:MSB, 0:LSB
Lch Data
Rch Data
Figure 3. Mode 0,1 Timing
MS0424-E-00
2005/09
- 16 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
