
[AK4671] 
MS0666-E-00 
2007/10 
- 49 - 
■
 EXT Slave Mode (PMPLL bit = “0”, M/S bit = “0”) 
When PMPLL bit is “0”, the AK4671 becomes EXT mode. Master clock is input from the MCKI pin, the internal PLL 
circuit is not operated. This mode is compatible with I/F of the normal audio CODEC. The clocks required to operate the 
AK4671 are MCKI (256fs, 384fs, 512fs, 768fs or 1024fs), LRCK (fs) and BICK (
≥
32fs). The master clock (MCKI) 
should be synchronized with LRCK. The phase between these clocks does not matter. The input frequency of MCKI is 
selected by FS2-0 bits (
Table 11
). 
In case that the CODEC is used without Audio I/F (like phone call), the CODEC can be operated by MCKI only. In this 
case, BICK and LRCK can be stopped. 
Mode 
FS3 bit 
FS2 bit 
FS1 bit 
FS0 bit 
MCKI Input 
Frequency 
256fs 
1024fs 
384fs 
768fs 
512fs 
256fs 
N/A 
(x: Don’t care, N/A: Not available) 
Sampling Frequency 
Range 
8kHz 
~
 48kHz 
8kHz 
~
 13kHz 
8kHz 
~
 48kHz 
8kHz 
~
 26kHz 
8kHz 
~
 26kHz 
8kHz 
~
 48kHz 
N/A 
0 
1 
4 
5 
6 
7 
x 
x
x 
x 
x
x
0 
0 
1 
1 
1 
1 
0 
0 
0 
0 
1 
1 
0 
1 
0 
1 
0 
1 
(default)
Others 
Others
Table 11. MCKI Frequency at EXT Slave Mode (PMPLL bit = “0”, M/S bit = “0”)
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 reduced by using higher frequency of the master clock. The S/N of the DAC output through 
LOUT/ROUT pins at fs=8kHz is shown in 
Table 12
. 
MCKI 
S/N 
(fs=8kHz, 20kHzLPF + A-weighted)
83dB 
93dB 
93dB 
256fs, 384fs 
512fs, 768fs 
1024fs 
Table 12. Relationship between MCKI and S/N of LOUT1/ROUT1 pins
MCKI should always be present whenever the ADC or DAC is in operation (PMADL bit = “1”, PMADR bit = “1”, 
PMDAL bit = “1” or PMDAR bit = “1”). If MCKI is not provided, the AK4671 may draw excess current and it is not 
possible to operate properly because utilizes dynamic refreshed logic internally. If MCKI is not present, the ADC and 
DAC should be in the power-down mode (PMADL=PMADR=PMDAL=PMDAR bits = “0”). 
AK4671 
DSP or 
μ
P
MCKI 
BICK 
LRCK 
SDTO 
SDTI 
BCLK 
LRCK 
SDTI 
SDTO 
MCKO 
1fs
≥
 32fs 
MCLK 
256fs, 384fs, 512fs, 
 768fs or 1024fs 
Figure 43. EXT Slave Mode