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LMV762Q-Q1: biasing voltage

Girish K76
Prodigy 90 points
Part Number: LMV762Q-Q1
Other Parts Discussed in Thread: LMV762, , ISO7721, ISO7720-Q1

Hai,

  I have a doubt regarding the biasing supply voltage of LMV762 comparator. Whether we can apply negative biasing voltage for this comparator? In the datasheet ,they have given V+ - V- as max 5.5
V and also give +5 and GND for all the diagrams Please clarify my query.

  • 0
    TI__Guru 51646 points

    Hello Girish,

    The LMV762Q-Q1 can be used in both single supply (GND and 5V) and split supply (+2.5 and -2.5V).

    As long as the difference between V- and V+ is no more than +5.5V, and V- is the most negative voltage, then it can be used as split supply.

    The applied input voltage must be between V- and 1.3V below V+, or 0 to 3.7V on a 0 and 5V single supply, or -2.5V to +1.2V on a +2.5/-2.5 split supply system.

    Keep in mind that the output swings "Low" to V- and not "GND" in a split supply system.

  • 0 in reply to Paul Grohe
    Prodigy 90 points

    Hai Paul Grohe,

       Thanks for your clarification on the matter. Subjected to this query,please see the attached SiC Mosfet gate driver design of TI.

    TI Designs: TIDA-01605 Automotive Dual-Channel, SiC MOSFET Gate Driver Reference Design With Two-Level Turnoff Protection

    (Note: The actual web link cannot be copied here)

    In the driver design,there is a feature called two-level turn-off given by TI.( See below the screen shot )

    The screenshot of the two level turn-off circuitry is shown above where you can see U8A and U8B comparators LMV762 with +Vcc at +5V and -Vcc at -4V..So V+-V- is coming at 9V which is contradictory to the datasheet values

    Also in the same design the comparator output is given to digital isolator ISO7721 . In case ,when the output of comparator clamps to -4V,the isolator does not have any provision to address this negative voltage .

    The max Vin referred in the datasheet is limited to -0.5 to Vcc+0.5.

    Please refer screenshot below.

    Kindly look into the TI design refer to Fig.6 shown above.

    Highlights: 

    Queries on 

    *  Negative biasing voltage for LMV762-Q1

    *  Negative VIN voltage for ISO7720-Q1

    Thanks....

  • 0 in reply to Girish K76
    TI__Mastermind 24090 points
    Agreed and we have notified owner of the Design. Closing since continued on another thread.
    Chuck