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MSP430F6721A: What is the highest noise free bits of MSP430F6721's 24 bit Delta-Sigma ADC SD24_B

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Replies: 3

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Part Number: MSP430F6721A

Hi team,

My customer is developing a O2 detection product, and they want to use MSP430F6721 as the control unit for it's low power consumption and 24 bit delta-sigma ADC. Now, they have one question, what is the highest noise free bits of the SD24_B when sampling a DC signal. From the datasheet, there is only AC performance parameters to calculate noise. So can you help me to get the DC performance(Noise free bit, effective resolution) of the SD24_B?

Thanks

Will

  • Hi Will,

    ENOB is dependent on what is being measured and DC signals are not characterized by the datasheet. Customers can run their own tests and calculate this using ENOB = log2 (Full-Scale Range / Input-Referred Noise) = 24 - log2(std.dev). Independent testing has found the ENOB of the SD24 to be ~16.7 bits for DC signals.

    Regards,
    Ryan

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  • In reply to Ryan Brown1:

    Hi Ryan,

    Thanks for your reply. And I want to know under what parameters that the SD24 can achieve 16.7bit. I mean what is the OSR and clock frequency that we can get 16.7 bit for this 24 bit ADC.

    Best regards,
    Will
  • In reply to Will Wang47:

    Hello Will,

    Use the highest SD24OSRx (1024), lowest SD24GAINx (1), and lowest sampling frequency (32 kHz) to achieve maximum ENOB. This will however make for a lengthy sampling time (32 ms).

    Regards,
    Ryan

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