AK7735EQ Datasheet, PDF (108/142 Pages) Asahi Kasei Microsystems – Dual DSP with 4chADC + 4chDAC + 4chSRC

[AK7735]
1-2. Down Sampling (0.167  FSO/FSI < 1.00)
Three kinds of filter mode can be selected by SRCFAUD bit and SRCFEC bit when down sampling.
Supported sampling rates are shown below. (Passband and Stopband are proportional to FSI when the
FSO/FSI ratios are same.)
1) Audio Mode (SRCFAUD bit = “1”, SRCFEC bit = “0”)
FSO
FSI FSO/FSI Passband Stopband
44.1kHz 48kHz 0.919 20.00kHz 24.10kHz
48kHz 88.2kHz 0.544 19.25kHz 26.23kHz
48kHz 96kHz
0.5 20.90kHz 27.00kHz
44.1kHz 88.2kHz 0.5 19.20kHz 24.81kHz
44.1kHz 96kHz 0.459 18.70kHz 25.00kHz
16kHz 44.1kHz 0.363 5.79kHz 7.95kHz
48kHz 192kHz 0.25 25.19kHz 34.60kHz
44.1kHz 192kHz 0.229 25.19kHz 34.60kHz
8kHz 48kHz 0.167 3.16kHz 4.66kHz
8kHz 44.1kHz 0.181 2.90kHz 4.28kHz
Table 64. Down Sampling Example (Audio Mode)
2) Voice Mode (SRCFAUD bit = “0”, SRCFEC bit = “0”)
FSO
FSI FSO/FSI Passband Stopband
24kHz 32kHz
0.75 10.94kHz 11.95kHz
16kHz 24kHz 0.667 7.22kHz 7.97kHz
16kHz 32kHz
0.5
7.14kHz 7.97kHz
8kHz 16kHz
0.5
3.57kHz 3.98kHz
16kHz 48kHz 0.333 6.80kHz 7.97kHz
8kHz 32kHz
0.25 3.26kHz 3.99kHz
Table 65. Down Sampling Example (Voice Mode)
3) Echo Canceller Mode (SRCFEC bit = “1”)
In echo canceller mode, the input signal should be attenuated sufficiently for more than FSO/2
frequency.
FSO
FSI FSO/FSI Passband Stopband
32kHz 44.1kHz 0.726 20.21kHz 23.89kHz
32kHz 48kHz 0.667 22.00kHz 26.00kHz
24kHz 44.1kHz 0.544 20.21kHz 23.89kHz
24kHz 48kHz
0.5 22.00kHz 26.00kHz
16kHz 44.1kHz 0.363 20.21kHz 23.89kHz
16kHz 48kHz 0.333 22.00kHz 26.00kHz
Table 66. Down Sampling Example (Echo Canceller Mode)
016014707-E-00
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2016/12