AK4536 Datasheet, PDF (24/59 Pages) Asahi Kasei Microsystems – 16-Bit Mono CODEC with ALC & MIC/SPK-AMP

ASAHI KASEI
[AK4536]
3) EXT, Slave Mode (PMPLL bit = “0”, M/S bit = “0”)
When PMPLL bit is “0”, the AK4536 becomes EXT mode. Master clock is input from 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 are MCKI
(256fs, 512fs or 1024fs), FCK (fs) and BICK (32fs∼). The master clock (MCKI) should be synchronized with FCK. The
phase between these clocks does not matter. The frequency of MCLK is selected by FS1-0 bits. (See Table 10)
Mode FS1 bit FS0 bit MCKI Input Frequency Sampling Frequency Range
0
0
0
256fs
7.35kHz ∼ 26kHz
1
0
1
1024fs
7.35kHz ∼ 13kHz
2
1
0
256fs
7.35kHz ∼ 26kHz
3
1
1
512fs
7.35kHz ∼ 26kHz
Table 10. MCKI Frequency at EXT, Slave Mode (PMPLL bit = “0”, M/S bit = “0”)
* FS2 bit is ignored.
Default
Audio interface format corresponds to Mode 1, 2 or 3.
The S/N of the DAC at low sampling frequencies is worse than at high sampling frequencies due to out-of-band noise.
When the out-of-band noise can be improved by using higher frequency of the master clock. The S/N of the DAC output
through AOUT amp at fs=8kHz is shown in Table 11.
MCKI
S/N
(fs=8kHz, 20kHzLPF + A-weight)
256fs
83dB
512fs
93dB
1024fs
93dB
Table 11. Relationship between MCLK and S/N of AOUT
The external clocks (MCKI, BICK and FCK) should always be present whenever the ADC or DAC is in operation
(PMADC bit = “1” or PMDAC bit = “1”). If these clocks are not provided, the AK4536 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 (PMADC bit = PMDAC bit = “0”).
In case of changing sampling frequency while DAC is normal operation, the change of sampling frequency should be done
after the input data is input to “0” or muted by DVOL7-0 bits.
AK4536
XTO
MCKI/XTI
256fs, 512fs or 1024fs
DSP or µP
MCLK
BICK
32fs, 64fs
BCLK
FCK
1fs
FCK
SDTO
SDTI
SDTI
SDTO
Figure 20. EXT, Slave Mode
MS0174-E-00
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2002/09