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Original question:

INA597: TINA simulation for offset temperature drift

INA597: is INA597 mux-friendly?

Jerry Chen
Expert 5110 points
Part Number: INA597
Other Parts Discussed in Thread: TMUX8109, INA592

Hi team,

I would like to check if INA597 is mux-frendly?  I would like to use TMUX8109 as input to INA597.

Thanks.

  • 0
    Guru 140200 points

    Hi Jerry,

    a mux-friendly amplifier is an amplifer which doesn't let flow a high spike current when the mux switches between the channels while the channels show highly different potentials. Such a high spike current could be the consequence of protection diodes between the inputs of a voltage follower buffering the output of mux, for instance, while not providing any current limiting through the protection diodes.

    The INA597 connects to the mux output via 12k or 6k resistors and provides an effective current limiting. So, from this point of view, the INA597 would be mux-friendly.

    Can you show how the TMUX8109 and the INA597 are powered in your circuit?

    Kai

  • +1
    TI__Guru 59191 points

    Hi Jerry,

    Kai has provided explanation about mux-friendly inputs if INA597 may be connected to a Mux with large differential inputs. INA592 belongs to difference amplifier family, and it

    doe not use antiparallel diodes at its analog input stage. With INA597's built-in internal resistors,  the design application should not "see"  switching or settling timing issues at its input due to inrush current when switching at Mux.  

    Enclosed is an article about how mux-friendly op amp is work around from the traditional CMOS amplifiers (with antiparallel diodes) between the inputs and input protection.  scheme.  

    https://www.ti.com/lit/an/sbot040c/sbot040c.pdf?ts=1647276299793&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FOPA828%253FkeyMatch%253DOPA828

    If you have additional questions, please let us know. 

    Best,

    Raymond