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LMP7704-SP: LMP7704-SP, LMP2012QML-SP and TLC2201-SP input impedance

Fernando Romero
Prodigy 10 points

Part Number: LMP7704-SP
Other Parts Discussed in Thread: LMP2012, TLC2201,

Dear Texas Instruments colleagues,

I am interested in the three products of the issue title, but I have not found the input impedance of these amplifiers. Could you help me with this request, please?

Thank you in advance.

  • 0
    TI__Expert 4560 points

    Hi Fernando,

    Unfortunately, the input impedance is not specified in the datasheet. However, you can extrapolate the input impedance by looking at the input bias current as a function of VCM.

    In Figures 5-17 of the LMP7704-SP datasheet, we see that the room temperature input impedance at Vs = 10V is ~17.4 TΩ from the equation below.

    The LMP2012 is an auto-zero device, and one I would not recommend if looking for high input impedance due to its auto-zero technology (page of the the LMP2012QML datasheet).

    The input impedance of the TLC2201 can be similarly derived by looking at Figure 6 of the TLC2201-SP datasheet (~ 8TΩ).

    Overall, I would recommend the LMP7704-SP device if looking for a very high input impedance device.

    Please let me know if you have further questions.

    Best regards,
    Carrie