KM34Z256 Three-Phase Power Meter - voltage sampling

[zbigniew_halat]

Hi,

I am building power meter from scratch on the TWR-KM34Z75M dev board, basing on document DRM162 ("KM34Z256 Three-Phase Power Meter Reference Design")  and I confused with Nyqusit frequency for voltage path (16-bit SAR ADC) mentioned in the document which is 3.072MHz

but software provided in the package has sampling set at 3kHz (AFE and SAR ADC seems to have the same sampling freq)

Does SAR ADC has some kind of modulator to oversampling the signal and this why document mentions 3.072MHz?

[FelipeGarcia · Accepted solution]

Hi zbigniew halat,

SAR ADC included in MKE32Z MCU does not have any oversampling module.

Regarding your other question, one of the clock sources the Analog Front End can be selected is a 6.144 MHz clock, as the Nyquist Theorem says the sampling rate must be at least 2fmax. That's why we the document mentions 3.072 MHz as the Nyquist frequency.

Hope it helps!

Best regards,

Felipe

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