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Original question:

LMV762: Application problem

LMV762: Unused Comparator Connections

Marvn Arcangel
Genius 12605 points
Part Number: LMV762

Hi Team,

The customer is using LMV762Q-Q1 dual package comparator in their project but they are not using one comparator section and they are asking what is the best way to terminate that unused comparator's input & output pins.

What I recommend was to follow the advice on this thread however, they have very limited space on their board, and following the advice on the thread would not be possible. Could you share the reason for connecting midsupply to one input? Is it necessary to connect one input to IC supply with divider network?

Can you also confirm if following the "Application Design Guidelines for LM339, LM393, TL331 Family Comparators (Rev. B)" Sec 5.1 Unused Comparator Connections would be okay? kindly refer to the image below:

Thank you for the support.

Regards,

Marvin

  • 0
    Guru 140200 points

    Hi Marvin,

    since ultra tiny SMD components are available, I must always smile when somebody is telling that there's not enough space on his printed circuit board. A "0402" resistor is only 0.5mm x 1.0mm, a "0201" is even only 0.3mm x 0.6mm. And this is not the smallest package available. And then there's still the backside of printed circuit board...

    Kai

  • 0 in reply to kai klaas69
    TI__Mastermind 25990 points

    Marvin

    Thanks for your post.  The goal is prevent the unused comparator for toggling which can happen if they are left as opens and they float to the same voltage potential.  I assume you are using some fixed reference voltage for the other channel.  So another suggestion would be to connect that reference voltage to the inverting pin of the unused channel and connect the non inverting to ground.  This will put the output in a known output state and the output of the unused comparator can just be left unconnected.  If the layout somehow makes it easier to connect the reference to the non-inverting pin of the unused channel, that is fine too.  Just ground the inverting input in that case and still leave the output unconnected.  Both options are appropriate options.

    Chuck