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How to change AD7176-2 sinc3 filter notch frequency?

Hi,

I used the register 0x28000060 and 0x28008060, and both of them change the sample rate and output data rate to 250kHz. But the sinc3 filter notch frequency of them at 50kHz. How can I change sinc3 filter notch frequency to 250kHz?

Thanks,

Alexyv

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  • Hi,

    I'm sorry what register do you mean? ODR is set using FILTCON register (0x28-0x2B) and this is a 16 bit register only. Unless you meant write 0x0060 to 0x28 or write 0x8060 to 0x28 but not sure if you written that correctly.

    To set sinc3 filter at 250ksps. You need to write 0x60 to FILTCONx register. If you write 0x8060 the part is configured in Sinc3 map mod. The data rate when on a single channel equals fMOD/(32 × FILTCON0[14:0]). But since the SING_CYC is also enabled the actual ODR is equal to settling time. But I think the notch should still be equal to 250ksps.

    You can see this in the Filter model or VE tool.

    AD7176-2 VE

    AD7176_2_filter_model.xls

    Thanks,

    Jellenie

Reply
  • Hi,

    I'm sorry what register do you mean? ODR is set using FILTCON register (0x28-0x2B) and this is a 16 bit register only. Unless you meant write 0x0060 to 0x28 or write 0x8060 to 0x28 but not sure if you written that correctly.

    To set sinc3 filter at 250ksps. You need to write 0x60 to FILTCONx register. If you write 0x8060 the part is configured in Sinc3 map mod. The data rate when on a single channel equals fMOD/(32 × FILTCON0[14:0]). But since the SING_CYC is also enabled the actual ODR is equal to settling time. But I think the notch should still be equal to 250ksps.

    You can see this in the Filter model or VE tool.

    AD7176-2 VE

    AD7176_2_filter_model.xls

    Thanks,

    Jellenie

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