RM48L950 ADC Question

R11

I have a question regarding the ADC offsets and error parameters in the datasheet. The table is shown below. Is E_TOT (Total unadjusted error after calibration) basically the sum of the effects of Z_SET, F_SET, E_DNL, and E_INL and then taking out any error or offset that can be removed due to the calibration process? In other words, would the total error before calibration be the sum of Z_SET, F_SET, E_DNL, and E_INL (or more likely maybe the root-sum-square of those terms)?

over 13 years ago

0 Sunil Oak over 13 years ago

TI__Mastermind 49120 points

Rustin,

The "after calibration" note needs to be removed from the description of the ETOT parameter. We ensure that the ADC meets the +/- 4 counts total error without requiring any offset calibration. We will address this in the next update to the datasheets.

Regards, Sunil

0 Jeffery Pfarr over 13 years ago in reply to Sunil Oak

TI__Genius 14317 points

Rustin,

Generally speaking, its possible to calibrate out ADC gain and offset errors at a specific temperature but you cannot calibrate out INL, DNL and quantizing errors. This particular device only has ADC offset calibration.

0 R11 over 13 years ago in reply to Jeffery Pfarr

Expert 1485 points

So, when analyzing accuracy, should we look at each of the offset and error parameters individually, or is it accurate to use the lumped +/- 4 count ETOT parameter as worst-case?

0 Jeffery Pfarr over 13 years ago in reply to R11

TI__Genius 14317 points

I would use ETOT and realize that the total error after offset calibration might be > 1 LSB better.

0 Sunil Oak over 13 years ago in reply to Jeffery Pfarr

TI__Mastermind 49120 points

I agree. The total unadjusted error does account for the effects of offset error, gain error and linearity error.

Regards, Sunil

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RM48L950 ADC Question