This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADC128S102: Gain error in +/-LSB

Part Number: ADC128S102

Hi Team,

A customer wants to know the gain error of ADC128S102 in +/-LSB.

Regards,

Danilo

  • Hello,

    The datasheet specifies the gain error in the "Full Scale Error" specification.  The specification varies for +3V and +5V supplies, but the maximum is the same for both at +/-2LSB.  Please review Table 6.5 in the datasheet for more information.

  • Hi Collin,

    At Section 11, page 22 of the datasheet, the Full Scale Error seems different from the Gain Error.

    Regards,

    Danilo 

  • Hello,

    I agree with the definitions at the end of the datasheet, but often have to do some "detective work" on these older products when there can be discrepancies between different areas of the datasheet.  I pulled down every revision of the product datasheet and none of them included a gain-error specification or graph so I think the definitions at the end were likely copied product-to-product.  Interestingly enough, the first revision of the datasheet did not include a "Full-Scale Error" definition, and only included a "Gain Error" definition, further adding to the likelihood that the definitions were copied around versus directly specific to this product.

    I still believe the intention of the FSE error specification in the ADC128S102 datasheet was to capture the gain-error, in addition to the full-scale error.  Therefore, I have good confidence that most devices will have gain-errors similar to the typical FSE specifications.

  • Thank you both for digging into this.  What did the original datasheet show as the gain error?

    If the intention of the FSE error specification in the ADC128S102 datasheet was to capture the gain-error, in addition to the full-scale error, then shouldn't I just subtract off the offset error from the FSE error, leaving the gain error?

    Was the offset error measured at 0V?  I didn't see in the datasheet where that was defined.

    Thanks!!!

  • Hello Joseph,

    The original datasheet did not have a line in the specification table for Gain Error, or its drift.  The only mention of gain-error was in the definition section of the datasheet.

    According to the definition, the offset error is measured near zero-scale:

    OFFSET ERROR is the deviation of the first code transition (000...000) to (000...001) from the ideal (i.e. GND + 0.5 LSB).