AK4665A Datasheet, PDF (14/52 Pages) Asahi Kasei Microsystems – 20-Bit Stereo CODEC with MIC/HP-AMP

ASAHI KASEI
[AK4665A]
For low sampling rates, outband noise causes S/N to degrade. S/N is improved by setting DFS bit to “1”. Table 3 shows
S/N of DAC output for both HP-Amp and Stereo-Lineout. When DFS bit is “1”, MCLK needs 512fs.
DFS
fs
MCLK
S/N (fs=8kHz, BW=20kHz, A-weighted)
HP-amp
Lineout
0 8kHz∼48kHz
256fs/512fs
84dB
84dB
Default
1 8kHz∼24kHz
512fs
90dB
88dB
Table 3. Relationship among fs, MCLK frequency and S/N of HP-amp and Lineout
„ Serial Data Interface
The AK4665A interfaces with external systems via the BICK, LRCK, SDTO and SDTI pins. Four data formats are
available and are selected by setting DIF1-0 bits (Table 4). Mode 0 of SDTI is compatible with existing 16bit DAC and
digital filters. Mode 1 of SDTI is a 20bit version of Mode 0. Mode 2 of SDTI is similar to AKM ADCs and many DSP
serial ports. Mode 3 is compatible with the I²S serial data protocol. In SDTI Modes 2 and 3, the following formats are also
valid: 16-bit data followed by four zeros and 18-bit data followed by two zeros. In all modes, the serial data is MSB first
and 2’s complement format.
Mode
0
1
2
3
DIF1
0
0
1
1
DIF0
0
1
0
1
SDTO
SDTI
20bit, MSB justified 16bit, LSB justified
20bit, MSB justified 20bit, LSB justified
20bit, MSB justified 20bit, MSB justified
IIS (I²S)
IIS (I²S)
Table 4. Audio Data Format
BICK
≥ 32fs
≥ 40fs
≥ 40fs
≥ 40fs
LRCK
H/L
H/L
H/L
L/H
Default
LRCK
BICK(64fs)
01 2
SDTO(o)
19 18
16 17 18 19 20 21
4 3 2 10
31 0 1 2
16 17 18 19 20 21
19 18
4 3 2 10
31 0 1
19
SDTI(i)
Don’t Care 15 14 13 12 11
1 0 Don’t Care 15 14 13 12 11
10
01 2
BICK(32fs)
8 9 10 11 12 13 14 15 0 1 2
8 9 10 11 12 13 14 15 0 1
SDTO(o)
19 18
12 11 10 9 8 7 6 5 4 19 18
12 11 10 9 8 7 6 5 4 19
SDTI(i)
15 14
8 7 6 5 4 3 2 1 0 15 14
Lch Data
Figure 8. Mode 0 Timing
8 7 6 5 4 3 2 1 0 15
Rch Data
MS0440-E-01
- 14 -
2006/05