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LMV861/LMV881 input resistance

na na78
Guru 16770 points
Other Parts Discussed in Thread: LMV861, LMV881

Hi

We are about to replace AD823 with TI product.

Additionally, we want to the following requirement.

- Input capacitance > 20pF

-Input resistance > 10Mohm

-Small package (smaller than 1.6mm x 2.9mm if possible)

We found the LMV861 and LMV881, but we can not get input resistance value on the datasheet.

1. LMV861 and LMV881 have Cin spec as follows

LMV861

Common mode input capacitance : 20pF

Differential mode input capacitance : 15pF

LMV881

Common mode input capacitance : 5pF

Differential mode input capacitance : 15pF

LMV881 has small value of common mode input capacitance than differential mode.  Is that correct?

2. What is the input resistance of LMV861 and LMV881?

BestRegards

  • 0
    TI__Guru 50016 points

    Hello NaNa,

    Both devices are CMOS inputs, so the input impedance will be in the tera-Ohms, so both will easily meet the 10Meg requirement.

    Regards

  • 0 in reply to Paul Grohe
    Guru 16770 points
    Hi Paul

    Thank you for your reply.

    Sorry, let me confirm the following.

    The description of Common mode input capacitance and Differential mode input capacitance value for LMV861 and LMV881 are as of the datasheet, right?

    BestRegards
  • 0 in reply to na na78
    TI__Guru 50016 points

    Hello,

    Yes. The LMV881 is based on the LMV861 core, but reduced in speed to save some current and added shutdown.

    Both devices have EMI input filters, which contributes to a large portion of the input capacitance.

    The input EMI filter of the 881 was modified to reduce CM capacitance as requested by the original customer.

    Regards,