[AK4753]
The S/N of the DAC at low sampling frequencies is worse than at high sampling frequencies due to out-of-band noise.
The out-of-band noise can be improved by using higher frequency of the master clock. The S/N of the DAC output
through LOUT1/ROUT1 and LOUT2/ROUT2 pins is shown in Table 10.
S/N
MCKI
(fs=8kHz, 20kHzLPF + A-weighted)
256fs
512fs
1024fs
87 dB
96 dB
97 dB
Table 10. Relationship between MCKI and S/N of LOUT1/ROUT1 and LOUT2/ROUT2 pins (SPC1-0 bits = “00”)
AK4753 DSP
256fs, 512fs or 1024fs
MCKI
MCLK
≥ 32fs
BCLK
LRCK
BICK
1fs
LRCK
SDTO
SDTI
Figure 24. EXT Slave Mode
■ EXT Master Mode (PMPLL bit = “0”, M/S bit = “1”)
The AK4753 becomes EXT Master Mode by setting PMPLL bit = “0” or the M/S bit = “1”. Master clock is input from
the XTI/MCKI pin or the crystal oscillator circuit is used, the internal PLL circuit is not operated. The clock required to
operate the AK4753 is XTI/MCKI (256fs, 512fs or 1024fs). The input frequency of XTI/MCKI is selected by FS1-0
bits (Table 11).
XTI/MCKI
Input Frequency
Sampling Frequency
Range
Mode
FS3-2 bits
FS1 bit
FS0 bit
0
1
2
3
x
x
x
x
0
0
1
1
0
1
0
1
256fs
1024fs
512fs
512fs
(default)
7.35kHz ∼ 48kHz
7.35kHz ∼ 13kHz
7.35kHz ∼ 26kHz
7.35kHz ∼ 26kHz
Table 11. XTI/MCKI Frequency at EXT Master Mode (PMPLL bit = “0”, M/S bit = “1”) (x: Don’t care)
The S/N of the DAC at low sampling frequencies is worse than at high sampling frequencies due to out-of-band noise.
The out-of-band noise can be improved by using higher frequency of the master clock. The S/N of the DAC output
through LOUT1/ROUT1 and LOUT2/ROUT2 pins is shown in Table 12.
S/N
XTI/MCKI
(fs=8kHz, 20kHzLPF + A-weighted)
256fs
512fs
1024fs
87 dB
96 dB
97 dB
Table 12. Relationship between XTI/MCKI and S/N of LOUT1/ROUT1 and LOUT2/ROUT2 pins (SPC1-0 bits = “00”)
MS1311-E-00
2011/07
- 24 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
