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gmeyer
Visitor II
September 25, 2003
Question

ST269 -vs- ST168 ADC timing

  • September 25, 2003
  • 2 replies
  • 642 views
Posted on September 25, 2003 at 14:04

ST269 -vs- ST168 ADC timing

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    2 replies

    G
    gmeyerAuthor
    Visitor II
    September 3, 2003
    Posted on September 03, 2003 at 21:09

    The document AN1313 states that there isn't a software difference between the anlog to digital converters of the ST269 and ST168 but when I look at the data sheets, the tcc value is off by a factor of two for a given ADSTC setting.

    Wouldn't we have to take this into account when porting to the ST269 so that we maintain the same sample time?
    C
    charles239955_st
    Visitor II
    September 25, 2003
    Posted on September 25, 2003 at 14:04

    In fact the total conversion time is the same. It is a ''documentation'' trick. 2 timings are defined depending on the doc you will have: either tsc (sample clock) or ts (sample time) with ts = 2x tsc.

    Then sometimes the formula for the total conversion time is:

    either tc = 14 tcc + ts +4 TCL

    either tc = 14 tcc + 2 tsc + 4 TCL

    In summary, for both devices the formula is:

    tc = 14 tcc + 2 tsc + 4 TCL and

    tsc = tcc for ADSTC = 00

    tsc = 2 tcc for ADSTC = 01

    tsc = 4 tcc for ADSTC = 10

    tsc = 8 tcc for ADSTC = 11

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