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F28M36P63C2: ADC input leakage current

John Simonsson97
Prodigy 100 points

Part Number: F28M36P63C2

The questions below are with reference to the device data sheet: SPRS825E –OCTOBER 2012–REVISED DECEMBER 2017

In table 5-36 ADC Electrical Characteristics there is a parameter, "Input leakage current", specified under the analog input section.

It is specified to +/-2 uA typically. My questions are:

  • Is it really this high typically and why in that case?
  • What is recommended maximum figures to consider over the temperature range -40 degrees to +125 degrees Celsius? This is good to know when the dimensioning the external passive network so not too high impedance is selected

Best Regards

John

  • 0
    TI__Guru 62975 points

    John Simonsson97 said:
    Is it really this high typically and why in that case?

    No, in my experience, it is nowhere near that high. 

    John Simonsson97 said:
    What is recommended maximum figures to consider over the temperature range -40 degrees to +125 degrees Celsius? This is good to know when the dimensioning the external passive network so not too high impedance is selected

    Unfortunately, the only Max value that we can officially guarantee across operating conditions is the +/- 2uA value in the datasheet due to how manufacturing QC is setup for this device.  Newer devices like F28004x have more realistic Max values.  Considering the 0.1uA Max leakage from F28004x for analog pins, I think it would be reasonable to design the passives assuming maybe 0.5uA of leakage.

    Also keep the ADC input model in mind when designing the passive network:

  • 0 in reply to tlee
    Prodigy 100 points

    Ok, thanks

    I can live with +/-2 uA as a max leakage current. In the datasheet it says though that this is the typical leakage current and that is why I asked for a maximum value.

    I was aware of the model in figure 10-12 from the reference manual.

    Best Regards
    John