AK4636 Datasheet, PDF (33/105 Pages) Asahi Kasei Microsystems – 16-Bit Mono CODEC with ALC & MIC/SPK/Video-AMP

[AK4636]
■ EXT Slave Mode (PMPLL bit = “0”, M/S bit = “0”)
When PMPLL bit is “0”, the AK4636 becomes EXT Slave 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
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 is not important. The input frequency of MCKI is selected by FS1-0 bits. (Table 11)
Mode
0
1
2
3
FS3-2 bits
FS1 bit FS0 bit MCKI Input Sampling Frequency
Frequency
Range
x
0
0
256fs
7.35kHz ≤ fs ≤ 48kHz (default)
x
0
1
1024fs
7.35kHz ≤ fs ≤ 13kHz
x
1
0
512fs
7.35kHz ≤ fs ≤ 26kHz
x
1
1
256fs
7.35kHz ≤ fs ≤ 48kHz
Table 11. MCKI Frequency at EXT Slave Mode (PMPLL bit = “0”, M/S bit = “0”) (x: Don’t care)
External Slave Mode does not support Mode 0 (DSP Mode) of Audio Interface Format.
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 master clock. (Table 12, Table 13)
MCKI S/N (fs = 8kHz, 20kHzLPF + A-weighted)
DAC →AOUT
256fs
81dB
512fs
89dB
1024fs
89dB
Table 12. Relationship between MCKI and S/N of AOUT and SPK-Amp
MCKI
Output Noise Level
(SVDD =3.3V,fs = 8kHz, 20kHzLPF + A-weighted)
SDTI → SPK-Amp
256fs
– 61dBV
512fs
– 75dBV
1024fs
– 83dBV
Table 13. Relationship between MCKI and Output Noise Level of SPK-Amp
The external clocks (MCKI, BICK and FCK) should always be present whenever the ADC or DAC or Programmable
Filter is in operation (PMADC bit = “1”, PMDM bit = “1”, PMDAC bit = “1” or PMPFIL bit = “1”). If these clocks are not
provided, the AK4636 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, DAC, SPK and Programmable Filter should be
in the power-down mode (PMADC bit = PMDM bit= PMDAC bit = PMPFIL bit = “0”).
AK4636
MCKO
MCKI
BICK
FCK
SDTO
SDTI
256fs, 512fs or 1024fs
DSP or μP
MCLK
≥ 32fs
BCLK
1fs
FCK
SDTI
SDTO
Figure 28. EXT Slave Mode
MS1012-E-01
- 33 -
2010/08