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INA149: INA149 (-Ep) output impedance

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Replies: 4

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Part Number: INA149

Hi,

I didn't find any curve about output impedance in INA149 (-EP) datasheet.

Does the spice model is representative for a "typical +25°C", on frequency range [1 ; 1Meg]Hz?

Best regards,

Emilien

  • The output impedance of INA149 is around 95ohms at 1MHz and it varies little with temperature.

    Marek Lis, MGTS
    Sr Application Engineer
    Precision Analog - TI Tucson

  • In reply to Marek Lis:

    Hi Marek,

    Thank you for this element.

    Spice model indicates: |Zout = 41,8 Ohm and arg(Zout) = 0 degrees  (FLAT curves) on [1;1Meg ] Hz

    The value of |Zout| = 95 Ohm , is true on frequency range [1;1Meg]Hz? (flat curve, with argument = 0 degree)?

    About temperature sensitivity : On range [-40; +90] °C ,  considering +/-50% of variation, seems realistics or not?

    Best regards ,

    Emilien

  • In reply to Emilien COULAUD:

    You need to change the vertical scale from dB to logarithmic to see it in ohms.  Even though the actual impedance may vary over frequency, its correct value of 95 ohms at unity bandwidth is most critical from stability point of you where the phase margin is the lowest.  As far as Zo variation over wafer process and temperature goes, it is not greater than +/-20%.

    Marek Lis, MGTS
    Sr Application Engineer
    Precision Analog - TI Tucson

  • In reply to Marek Lis:

    Hi Marek,

    Thank you for your help.

    Best regards,

    Emilien

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