AK4635 Datasheet, PDF (33/81 Pages) Asahi Kasei Microsystems – 16-Bit Mono CODEC with ALC & MIC/SPK/Video-AMP

[AK4635]
■ Audio Interface Format
Four types of data formats are available and are selected by setting the DIF1-0 bits. (Table 16) In all modes, the serial data
is MSB first, 2’s complement format. Audio interface formats can be used in both master and slave modes. FCK and
BICK are output from the AK4635 in master mode, but must be input to the AK4635 in slave mode.
In Mode 1-3, the SDTO is clocked out on the falling edge of BICK and the SDTI is latched on the rising edge.
Mode
0
1
2
3
DIF1
0
0
1
1
DIF0
0
1
0
1
SDTO (ADC) SDTI (DAC)
BICK
DSP Mode
DSP Mode
≥ 16fs
MSB justified MSB justified ≥ 32fs
MSB justified MSB justified
I²S compatible I²S compatible
≥ 32fs
≥ 32fs
Table 16. Audio Interface Format
Figure
See Table 17
Figure 29
Figure 30
Figure 31
(default)
In Mode0 (DSP mode), the audio I/F timing is changed by BCKP and MSBS bits.
When BCKP bit is “0”, SDTO data is output by rising edge of BICK, SDTI data is latched by falling edge of BICK.
When BCKP bit is “1”, SDTO data is output by falling edge of BICK, SDTI data is latched by rising edge of BICK.
MSB data position of SDTO and SDTI can be shifted by MSBS bit. The shifted period is a half of BICK.
MSBS bit BCKP bit
Audio Interface Format
0
0
Figure 32
0
1
Figure 33
1
0
Figure 34
1
1
Figure 35
Table 17. Audio Interface Format in Mode 0
(default)
If 16-bit data, the output of ADC, is converted to 8-bit data by removing LSB 8-bit, “−1” at 16bit data is converted to “−1”
at 8-bit data. And when the DAC playbacks this 8-bit data, “−1” at 8-bit data will be converted to “−256” at 16-bit data
and this is a large offset. This offset can be removed by adding the offset of “128” to 16-bit data before converting to 8-bit
data.
FCK
0 1 2 3 8 9 10 11 12 13 14 15 0 1 2 3 8 9 10 11 12 13 14 15 0 1
BICK(32fs)
SDT O( o)
15 14 13 8 7 6 5 4 3 2 1 0
15
SD T I( i)
15 14 13
0 1 23
BICK(64fs)
SDT O( o)
15 14 13
7 65 4 3 21 0
14 15 16 17 18
31 0 1 2 3
2 10
Don’t Care
14 15 16 17 18
15
31 0 1
15
SD T I( i)
Don’t Care
15:MSB, 0:LSB
Data
15 14
10
1/fs
Figure 29. Mode 1 Timing
Don’t Care
Rev. 0.6
- 33 -
2007/10