Can we configure the AD7768-1 as an ADC with an adjustable sampling frequency?

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Can we configure the AD7768-1 as an ADC with an adjustable sampling frequency?

Can we directly switch the sampling frequency of the chip through the program? I mean don't change the external hardware device. Simply use the FPGA to input a command to the ADC via SPI .Because I see that the AD7768-1 provides three power modes and kinds of modulator and  filters.

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  • Hi,

    There are 4 MCLK divide options that can be set via SPI which will directly change the sampling rate. The question is, do you want to change the sampling rate or the output data rate? The AD7768-1 is a Sigma-Delta ADC which is over-sampled. 

    The output data rate (ODR) can be adjusted by changing the MCLK_div setting and the decimation rate. The output data rates achievable in this scenario would be powers of two. For example, 256kSPS, 128kSPS, 64kSPS. If an alternative output data rate is needed you could also change the MCLK provided to the part.

    ODR = MCLK/(MCLK_DIV × Decimation Rate)

    Regards

    Niall

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  • HI,

    Thanks for your reply!

      Some people wants me to use the AD7768-1 chip to make a collector that can select the sampling frequency.But I found that there is only a description of the ODR in the data sheet, not sampling frequency.So what is the correspondence between sampling frequency and ODR? if the requirement is that sampling frequency just be less than one-half of the ODR?

    And another question i want to ask is that,if its  make sense to do this  in your opinion.?

    Because I think that selecting the sampling frequency as a high frequency can still collect signals lower than the set frequency....

    lizhe.