AK5397 Datasheet, PDF (33/44 Pages) Asahi Kasei Microsystems – 32-Bit Stereo Premium ADC

[AK5397]
■ Digital High Pass Filter
The AK5397 has a digital high pass filter for DC offset cancellation. The high pass filter is controlled by
the HPFE pin as shown by Table 8 and is reflected in both SDTO1 and SDTO2. The cut-off frequency of
the high pass filter is fixed 1.0Hz. The high pass filter is disabled in fs=384KHz mode or fs=768KHz
mode, and the setting of HPFE pin is ignored. The high pass filter setting should only be changed when
the PDN pin = “L”.
HPFE pin
HPF
L
OFF
H
ON
Table 8. Setting of HPF
■ Overflow Detection
The AK5397 has an overflow detect function for the analog input. The OVF pin becomes “H” for one cycle
after LRCK “↑” if either channel overflows (more than -0.276dBFS). The OVF output for overflowed
analog input has the same group delay as the ADC. The OVF pin is “L” for 1028/fs
(=21.41ms@fs=48kHz) after the PDN pin=“”, and then overflow detection is enabled.
■ Mono Mode
When the MONO pin is set to “H”, the AK5397 becomes MONO mode. In the Mono mode, L channel and
R channel data are summed digitally and divided into half. The dynamic range and S/N can be improved
about 3dB when the same analog signal is input to left and right channels. In this mode, the left and right
channel data on SDTO1 and SDTO2 are the same data.
MONO pin SDTO1/2 Output Data
L
Stereo Mode
H
Mono Mode
Table 9. The setting of MONO mode.
LRCK
BICK(64fs)
0 1 2 13 14 15 16 17 18 29 30 31 32 _{33 34} 44 45 46 47 48 49 61 62 63 0 1
SDTO1/2(Normal) 31 30
18 17 16 15 14
2 1 0 31 30
18 17 16 15 14 8 2 1 0 31
18
16 15 14
31: MSB, 0:LSB @ Lch 32bit
31: MSB, 0:LSB @ Rch 32bit
SDTO1/2(MONO) 31 30
18 17 16 15 14
2 1 0 31 30
18 17 16 15 14
2 1 0 31
18
16 15 14
31: MSB, 0:LSB @ Lch 32bit
Same Data
18
16 15 14
31: MSB, 0:LSB @ Rch 32bit
Figure 36. Audio Interface Timing (Normal mode or MONO mode, MSB justified)
014011535-E-00
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2014/11