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ADS5263 error

NAOKI AOYAMA
Guru 11215 points

Other Parts Discussed in Thread: ADS5263

Hello,

My customer uses the ADS5263.

He checked a error characteristics with repeat test as attached file.

5852.ADS5263_test_condition.pdf

The error is about 2LSB. It is occurred when input signal from 9200LSB to 10000LSB, from 10200LSB to

11000LSB, from 11000LSB to 11800LSB and from 12500LSB to 13300LSB.

It is not occurred from 7800LSB to 8500LSB and 13500LSB to 14200LSB.

The ADS5263 has 4ch converters. But the error is occurred at particular channel.

He has some questions.

Q1) The error is 2LSB. Is it a reasonable value?

Q2) Does the error characteristic change with LSB level?

Q3) Is there a possibility that the particular channel occur the error?

Regards,

Naoki Aoyama

  • 0
    TI__Genius 14540 points

    Hi,

    We have received your questions regarding the ADS5263 and hope to have answers for you very soon.

    Thanks

  • 0 in reply to Christian Yots
    TI__Genius 14540 points

    Hi,

    [Question 1]

    The error is 2LSB. Is it a reasonable value?

     

    [Response 1]  

    Yes this is a reasonable value as it corresponds exactly with the error shown in Figure 36 of the datasheet.  Code errors, or breaks in INL, will be observed when the input signal crosses thresholds of the comparators inside stage 1 of flash ADC.  The errors or glitches show to be 2LSB which corresponds to the absolute value of INL as shown in Figure 36.  The only difference is where the code position where the errors occur.  Since the INL curve is highly dependent on the change of input signal from sample N to sample N+1, it is, therefore, dependent on the type of input signal provided.  Based on the plot provided it appears user is applying a ramp waveform whereas TI's convention for characterizing ADC linearity is to provide a sine wave input and use best fit algorithm.  

     

    [Question 2]

    Does the error characteristic change with LSB level?

     

    [Response 2]  

    The error amount is fixed in mV. Now if you go from 16b LSB to 15b LSB, the same error will be represented by half the  LSBs (i.e. 2 LSBs in 16-bit level will change to 1 LSB in 15-bit level).

     

    [Question 3]

    Is there a possibility that the particular channel occur the error?

     

    [Response 3]  

    All  channels should be statistically the same for all parameters.   In the case that they are not,  the specifications and figures of the datasheet reflect the worse case channel.  

     

    Thanks

    Christian

  • 0 in reply to Christian Yots
    Guru 11215 points

    Hi Christian,

    Thank you for your reply and information in detail.

    I will feedback to my customer the information.

    Thanks

    Naoki