AK4951AEN Datasheet, PDF (34/105 Pages) Asahi Kasei Microsystems – 24bit Stereo CODEC with MIC/HP/SPK-AMP

[AK4951A]
■ Audio Interface Format
Four types of data formats are available and selected by setting the DIF1-0 bits (Table 19). In all modes,
the serial data is MSB first, 2’s complement format. Audio interface formats are supported in both master
and slave modes. LRCK and BICK are output from the AK4951A in master mode, but must be input to the
AK4951A in slave mode. The SDTO is clocked out on the falling edge (“”) of BICK and the SDTI is
latched on the rising edge (“”) of BICK.
Mode
0
1
2
3
DIF1
bit
0
0
1
1
DIF0
bit
0
1
0
1
Table 19. Audio Interface Format
SDTO (ADC)
SDTI (DAC)
BICK
Figure
24bit MSB justified
24bit MSB justified
24bit MSB justified
I²S Compatible
24bit LSB justified
16bit LSB justified
24bit MSB justified
I²S Compatible
 48fs
 32fs
 48fs
=32fs or  48fs
Figure 21
Figure 22
Figure 23
Figure 24
(default)
If 24-bit (16-bit) data, the output of ADC, is converted to 8-bit data by removing LSB 16-bit (8-bit), “1” at
24-bit (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 “65536” at 24-bit (“256” at 16-bit) data which is a large offset. This offset
can be removed by adding the offset of “32768” at 24-bit (“128” at 16-bit) to 24-bit (16-bit) data before
converting to 8-bit data.
LRCK
01 2
BICK(64fs)
8 9 10
24 25
SDTO(o)
23 22
16 15 14
0
31 0 1 2
8 9 10
24 25
23 22
16 15 14
0
31 0 1
23
SDTI(i)
Don’t Care 23 22
87
1 0 Don’t Care
23:MSB, 0:LSB
Lch Data
Figure 21. Mode 0 Timing
23 22
87
Rch Data
10
LRCK
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)
SDTO(o)
SDTI(i)
23 22 21
15 14 13
15 14 13 12 11 10 9 8 23 22 21
32
7 6 5 4 3 2 1 0 15 14 13
15 14 13 12 11 10 9 8 23
7 6 5 4 3 2 1 0 15
0 1 2 3 15 16 17 18 23 24 30 31 0 1 2 3 15 16 17 18 23 24 30 31 0 1
BICK(64fs)
SDTO(o)
23 22 21
87 6 5 0
23 22 21
87 6 5 0
23
SDTI(i)
Don’t Care
15 14 13 8 2 1 0 Don’t Care
24bit: 23:MSB, 0:LSB
16bit: 15: MSB, 0:LSB
Lch Data
Figure 22. Mode 1 Timing
016001936-E-00
- 34 -
15 14 13 8 2 1 0
Rch Data
2016/03