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AK4646EZ Datasheet, PDF (27/78 Pages) Asahi Kasei Microsystems – Stereo CODEC with MIC/SPK-AMP | |||
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[AK4646EZ]
â System Reset
Upon power-up, the PDN pin should be âLâ and be changed from âLâ to âHâ after all power supply are supplied. âLâ time
of 150ns or more is needed to reset in the AK4646. This ensures that all internal registers reset to their initial values.
The ADC enters an initialization cycle that starts when the PMADL or PMADR bit is changed from â0â to â1â. The
initialization cycle time is 1059/fs=24ms@fs=44.1kHz. During the initialization cycle, the ADC digital data outputs of
both channels are forced to a 2's compliment, â0â. The ADC output reflects the analog input signal after the initialization
cycle is complete.
The DAC outputs unexpected data after PMDAC bit â0â â â1â until 67/fs = 1.52ms@fs = 44.1kHz, then the DAC starts
outputting the normal voltage.
(Note) The initial data of ADC has the offset data that depends on the condition of the microphone and the cut-off
frequency of HPF. If this offset isnât small, donât use the initial data of ADC.
â Audio Interface Format
Three types of data formats are available and selected by setting the DIF1-0 bits (Table 16). In all modes, the serial data is
MSB first, 2âs complement format. Audio interface formats can be used in both master and slave modes. LRCK and BICK
are output from the AK4646 in master mode, but must be input to the AK4646 in slave mode. The SDTO is clocked out on
the falling edge (âââ) of BICK and the SDTI is latched on the rising edge (âââ).
Mode
0
1
2
3
DIF1 bit
0
0
1
1
DIF0 bit SDTO (ADC) SDTI (DAC) BICK
0
N/A
N/A
N/A
1
MSB justified LSB justified ⥠32fs
0
MSB justified MSB justified ⥠32fs
1
I2S compatible I2S compatible ⥠32fs
Table 16. Audio Interface Format (N/A: Not available)
Figure
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Figure 18
Figure 19
Figure 20
(default)
If 16-bit data that ADC outputs is converted to 8-bit data by removing LSB 8-bit, ââ1â at 16bit data is converted to ââ1â
at 8-bit data. And when the DAC playbacks this 8-bit data, ââ1â at 8-bit data will be converted to ââ256â at 16-bit data
which is a large offset. This offset can be removed by adding the offset of â128â to 16-bit data before converting to 8-bit
data.
MS0630-E-00
- 27 -
2007/06
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