AK4691EG AKM [Asahi Kasei Microsystems], AK4691EG Datasheet - Page 26

• Manufacturer Part Number: AK4691EG
• Description: 4ch ADC + 2ch DAC with MIC/HP/SPK-AMP
• Manufacturer: AKM [Asahi Kasei Microsystems]

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When PMPLL bit is “0”, the AK4691 becomes EXT mode. Master clock is input directly from MCKI pin without the
internal PLL circuit. This mode is compatible with I/F of the normal audio CODEC. The clocks required to operate are
MCKI (256fs, 512fs 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 FS1-0 bits
11).
Table 11. MCKI Frequency at EXT Slave Mode (PMPLL bit = “0”, M/S bit = “0”), (N/A: Not available, 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 reduced by using higher frequency of the master clock. The S/N of the DAC output through
the LOUT/ROUT pins at fs=8kHz is shown in
The external clocks (MCKI, BICK and LRCK) should always be present whenever the ADC or DAC is in operation
(PMADC1 bit = “1”, PMADC2 bit = “1” or PMDAC bit = “1”). If these clocks are not provided, the AK4691 may draw
excess current and it is not possible to operate properly because utilizes dynamic refreshed logic internally. If the external
clocks are not present, the ADC and DAC should be in the power-down mode (PMADC1=PMADC2=PMDAC bits =
“0”).
MS0672-E-00
EXT Slave Mode (PMPLL bit = “0”, M/S bit = “0”)
Others
Mode
0
1
2
3
FS3-2 bits
x
x
x
x
Table 12. Relationship between MCKI and S/N of LOUT/ROUT pins
Mode
0
2
3
1
AK4691
Others
FS1 bit
MCKO
MCKI
BICK
LRCK
SDTO1/2
SDTI
0
0
1
1
1024fs
MCKI
256fs
512fs
512fs
Figure 16. EXT Slave Mode
Table
FS0 bit
256fs, 512fs or 1024fs
0
1
0
1
12.
- 26 -
≥ 32fs
1fs
(fs=8kHz, 20kHzLPF + A-weighted)
MCKI Input
Frequency
1024fs
256fs
512fs
512fs
N/A
MCLK
BCLK
LRCK
SDTI1/2
SDTO
80dB
90dB
90dB
S/N
DSP or μP
Sampling Frequency
7.35kHz ∼ 48kHz
7.35kHz ∼ 13kHz
7.35kHz ∼ 48kHz
7.35kHz ∼ 26kHz
Range
N/A
(default)
[AK4691]
2007/11
(Table