Other Parts Discussed in Thread: ADS8681, BQ40Z50-R2
Hello; Can you please clarify a couple questions:
1. The datasheet lists the CC ADC resolution on page 11 as: (1) 1 LSB = VREF1/(10 × 2N) = 1.215/(10 × 215) = 3.71 μV
and the other ADC as (1) 1 LSB = VREF1/(2N) = 1.225/(215) = 37.4 μV (when tCONV = 31.25 ms)??
But since the 1.225 reference is labeled "Vref2" in Table 7.28, shall I assume this is a typo?
2. I'm confused about the accuracy spec's listed in the 40z50 reference manual, but I may be misunderstanding them. Specifically, I'm concerned about the INL values listed for the CC ADC: "Integral non-linearity(1) 16-bit, best fit over input voltage range ±5.2 ±22.3 LSB ". Since INL errors cannot be calibrated out, can you confirm/explain the impact this INL error has on the IT accuracy?
Generally ADCs used in d.c. applications should be have INL specified with the "End Point" method, since the "Best Fit" method tends to hide the worst case. And since the device is calibrated (offset/gain), the best fit line wouldn't these two points anyway. I note that some (or all ?) your SAR ADC's do in fact specify INL using End Point (see ADS8681). But your SigD converters specify it as "ppmFSR"...and they're typically very good (e.g. 4 ppmfsr).
Thanks!
