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ADS127L11: Quantify reduced settling time due to precharge buffers?

Lauren Mayfield
Expert 7985 points
Part Number: ADS127L11


Tool/software:

Hi team,

My customer has the following question-

the datasheet states “The ADC incorporates precharge buffers that reduce the settling and bandwidth requirement of the analog input driver.”

Is there a way to quantify this reduction in settling time requirement? 

Thanks,

Lauren

  • 0
    TI__Mastermind 47750 points

    Hi Lauren,

    Using the recommended input RC filter as shown in Figure 9-6, the input model can be approximated simply by an input resistance of approximately 10Mohm.  In practice, an input amplifier with a bandwidth of 8MHz or higher will work well.

    Pre-charge buffers OFF:

    f-mod=12.8MHz for High speed mode

    Cin=7.4pF

    With Pre-charge buffers ON, the equivalent input resistance is increased by 1000x:

    Regards,
    Keith Nicholas
    Precision ADC Applications