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PSoC 4 MCU

YoIs_1298666
Contributor II

Hello,

I tried LPF in Scan _ADC_v3_10 in various ways.

In conclusion, the minimum corner freq(kHz) was 0.8kHz like below.

pastedImage_1.png

pastedImage_2.pngpastedImage_3.png

We could not set lower frequency than 0.8kHz. Is this correct?

Best regards,

Yocchi

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1 Solution
DineshbabuM_66
Employee

Hi Yocchi-san,

40 Hz corner frequency is not achievable using UAB filter due to the minimum sample rate requirement (50 kHz) and maximum allowed OSR (200).  The warning in your previous screen shot is due to achieved corner frequency using discrete cap values is greater than 5% from the desired value.  Setting the corner frequency to 0.44 kHz fits within 5% margin as below.

pastedImage_0.png

Thanks,

Dinesh

View solution in original post

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5 Replies
Vasanth
Moderator
Moderator

Hello Yocchi san,

What is the adc scan rate and filter filter rate you require ? ,

Best Regards

Vasanth

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DineshbabuM_66
Employee

Hi Yocchi-san,

When using 83.3 ksps sample rate of filter(from your captures), considering a max OSR of 200, the filter cut-off can go down to 0.4 kHz.  Could you please let me know what is your desired filter cut-off and ADC sample rate?

Thanks,

Dinesh

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YoIs_1298666
Contributor II

Hello Vasanth-san, Dinesh-san,

Please see the below.

pastedImage_1.png

We hope the cut off frequency 40Hz.

and if we set cutt off frequcncy 420Hz, we have more than 5% off target.

pastedImage_2.png

Best regards,

Yocchi

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DineshbabuM_66
Employee

Hi Yocchi-san,

40 Hz corner frequency is not achievable using UAB filter due to the minimum sample rate requirement (50 kHz) and maximum allowed OSR (200).  The warning in your previous screen shot is due to achieved corner frequency using discrete cap values is greater than 5% from the desired value.  Setting the corner frequency to 0.44 kHz fits within 5% margin as below.

pastedImage_0.png

Thanks,

Dinesh

View solution in original post

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YoIs_1298666
Contributor II

Dinesh-san,

OK. Thank you.

Best regards,

Yocchi

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