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recommended Input Voltage Range.

HS FAE Germany
Mastermind 30505 points
Part Number: LM7321-Q1
Other Parts Discussed in Thread: LM7321

Hello,
the common mode voltage Vcm can reach supply voltage in customer application (or also overshot). Therefor customer need following parameter:
- Vcm max rating (needed so that the IC will not be damaged) which is included in the d/s:

- recommended input voltage range (needed so that IC will function correct). This parameter is not included in the d/s. Can you give a recommendation?

Regards Holger

  • 0
    TI__Guru*** 140136 points

    Hello Roger,

    The first line in the data sheet says "Rail-to-Rail Input". That is V- to V+

    Data sheet figures 8 to 16 show typical behavior for VCM range

    In table 7.1, the minimum and maximum are swapped in this line

  • 0 in reply to Ron Michallick
    TI__Mastermind 30505 points

     Hello Roger,

    1. Yes, LM7321 is an input/output rail-to-rail OP.
    2. Figures 6 – 16 indicate the behavior Vcm respected to input offset Vos, but I think this is not the answer…
    3. This is the max. rating, which the input voltage must not exceed.

    The background of his question:
    They are using the LM7321Q1 in the project.
    Now due to shortage they have to find an alternative chip and the OPAx991Q1 could fit.

    As mentioned, the common mode input voltage Vcm could beyond the input voltage, hence, this Vcm is a key parameter for our application.

    In the comparison the datasheets they found:

    1. In OPAx991Q1 datasheet the recommended input voltage is specified as above:
    2. In LM7321 datasheet he cannot find such parameter. So what is the recommended input voltage?

    Can we have a call with the customer today?

    Regards, Holger

  • 0 in reply to HS FAE Germany
    Guru 243980 points

    The recommended input voltage range is implied by the common-mode voltage range. (In the x991 datasheet, VCM and recommended VI are the same.)

  • 0
    Guru 140200 points

    Hi Holger,

    HS FAE Germany said:
    - recommended input voltage range (needed so that IC will function correct). This parameter is not included in the d/s. Can you give a recommendation?

    The recommended common mode input voltage range is specified in the datasheet of LM7321. See the CMVR specification in the sections 7.5, 7.6 and 7.7.

    Kai