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ADS7029-Q1: Pin Leakage and Pu/Pd resistors

David Shumate
Expert 5845 points
Part Number: ADS7029-Q1

Hi Team,

My customer is doing worst case analysis for the ADS7029-Q1. For this analysis, could we get your help with min, typ and Max Leakage of pins AINM and AINP?

Also if applicable, can you share Pull up and Pull down resistor value for above two pins?

Thanks,

David

  • 0
    TI__Guru**** 170395 points

    Hi David,

    There is nothing in the datasheet about leakage, and looking at the sampling details, it really should not be an issue here.  The ADS7029 goes into sample mode (tACQ) directly after is finishes a conversion (see Figure 1).  There are no internal pull-up/down resistors and no need for external ones.

  • 0 in reply to Tom Hendrick
    TI__Expert 5845 points

    Hi Tom,

    Thanks very much for the reply! Sorry I'm not a ADC expert, how does sample mode directly after finishing conversion relate or dismiss the need to know about leakage? 

    Our design will have inline resistors before the ADC so I believe the real concern here is error introduced by IR drop due to leakage current across these resistors. 

    Best,

    David

  • 0 in reply to David Shumate
    TI__Guru**** 170395 points

    Hi David,

    Generally speaking, leakage would be a concern when the voltage on the sample/hold cap starts to drop to a point where the conversion results can be influenced.  This is usually something you'd see in a device with a multiplexor or a sample mechanism that is delayed from the point at which the conversion starts.  Similar parts that have leakage values posted show +/-1uA, with a 'not production tested' note.  You would not see anything worse than that with the ADS7029.

    On the series resistor front, please consider a circuit similar to what is shown in Figure 37/38.  You need to be aware of the charge kick-back you can see from the sample/hold switch.