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TLA2528: What's the analog input impedance?

Alberto Ferrero64
Prodigy 50 points
Part Number: TLA2528

Dear Sirs,

in TLA2528 datasheet I can't find the input impedance of each analog input, nor the max input current absorbed by each analog input. I'd like to use this ADC to read from a source with an output impedance around 90KOhm and I'd like to calculate the max reading error if I don't buffer the output.

Many thanks in advance,

Alberto.

  • 0
    TI__Mastermind 25030 points

    Hello,

    the TLA2528 is a SAR architecture device, this means it uses a switching capacitor circuit to sample the input. because of this the impedance is not specified.

    This depends on the sampling frequency used for the device. The TLA2528 has a TINA reference model, which is a spice simulator that can be used to see if the input is settling at different sampling speeds. you can also test it out with various inputs. If you use a TI op amp, you can use the TINA spice model for the buffer to measure results. 

    What is the sampling rate of the device? and the nature of the signal source (AC or DC)

    Regards

    Cynthia