ak4644 AKM Semiconductor, Inc., ak4644 Datasheet - Page 30

• Manufacturer Part Number: ak4644
• Description: Stereo Codec With Mic/hp/rcv-amp
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
The AK4644 becomes EXT Master Mode by setting PMPLL bit = “0” and M/S bit = “1”. Master clock is input from
MCKI pin, the internal PLL circuit is not operated. The clock required to operate is MCKI (256fs, 512fs or 1024fs). The
input frequency of MCKI is selected by FS1-0 bits (see Table 14).
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 LOUT/ROUT pins at fs=8kHz is shown in Table 15.
MCKI should always be present whenever the ADC or DAC is in operation (PMADL bit = “1”, PMADR bit = “1” or
PMDAC bit = “1”). If MCKI is not provided, the AK4644 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=PMDAC bits = “0”).
MS0477-E-01
EXT Master Mode (PMPLL bit = “0”, M/S bit = “1”)
Mode
0
1
2
3
Table 14. MCKI Frequency at EXT Master Mode (PMPLL bit = “0”, M/S bit = “1”)
FS3-2 bits
Don’t care
Don’t care
Don’t care
Don’t care
Table 15. Relationship between MCKI and S/N of LOUT/ROUT pins
AK4644
Table 16. BICK Output Frequency at Master Mode
1024fs
MCKI
256fs
512fs
FS1 bit
BCKO bit
MCKO
MCKI
BICK
LRCK
SDTO
SDTI
0
0
1
1
0
1
Figure 24. EXT Master Mode
(fs=8kHz, 20kHzLPF + A-weighted)
FS0 bit
256fs, 512fs or 1024fs
0
1
0
1
32fs or 64fs
BICK Output
Frequency
- 30 -
1fs
32fs
64fs
MCKI Input
83dB
93dB
93dB
S/N
Frequency
1024fs
256fs
256fs
512fs
MCLK
BCLK
LRCK
SDTI
SDTO
Default
DSP or µP
Sampling Frequency
7.35kHz ∼ 48kHz
7.35kHz ∼ 13kHz
7.35kHz ∼ 48kHz
7.35kHz ∼ 26kHz
Range
Default
[AK4644]
2006/10