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TMS320F280049: ADC sample window

Luke Chen
Expert 5090 points
Part Number: TMS320F280049

Hi champs,

According to datasheet, the minimum ADC sample window is 75ns. This means that if customer set sample windows less than 75ns, it will cause an inaccurate ADC conversion result, is this correct?

Is there any side effect if sample window less than 75ns, beside inaccurate result?

Regards,

Luke

  • +1
    TI__Guru 60865 points

    Hi Luke,

    First, it important to note that the minimum S+H can only be used with a high bandwidth and low impedance driving circuit.  You can get an estimate of the S+H required for a particular driving circuit by using the formula in the TRM "Choosing an Acquisition Window Duration" section or you can get a very good estimate using simulation methods from the following app note: https://www.ti.com/lit/an/spract6/spract6.pdf.

    You can roughly estimate the additional error due to inadequate settling via simulation, but if the S+H time is lower than the minimum, additional unmodeled errors may start to dominate.  Overall, if the S+H is below the minimum, you would expect significant additional error in the conversion result.  You should still expect to get some conversion result as long as the S+H is longer than 1 ADCCLK.