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

Will Wang47

Part Number: MSP430F6721A
Other Parts Discussed in Thread: MSP430F6721

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

over 6 years ago

0 Ryan Brown1 over 6 years ago

TI__Guru**** 202106 points

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

0 Will Wang47 over 6 years ago in reply to Ryan Brown1

TI__Expert 5470 points

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

0 Ryan Brown1 over 6 years ago in reply to Will Wang47

TI__Guru**** 202106 points

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