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TLC3702: What to do with unused comparator?

Brian B
Prodigy 60 points
Part Number: TLC3702

I selected the TLC3702 part for reasons other than it being a dual comparator, and only need one of the two comparators on the device. What should be done with the unusued comparator? Can I leave the input and output pins open, or should they be grounded (through resistors?)? The datasheet speaks nothing of this, other than "the inputs should always remain within the supply rails..." which doesn't necessarily translate to open pins being a bad thing.

Thanks in advance!

  • 0
    TI__Mastermind 49906 points

    Hello Brian,

    Leave the output floating.

    Do not ground both inputs - as this can cause "chatter" if the device's internal offset is near zero. Do not let them float as this can cause similar problems (random output "flops"). Instead, force the output to a known state.

    Ground one input and tie the other input to a convenient voltage between GND and 1V below the comparator supply voltage. Perhaps borrowing a (somewhat) stable voltage from the other channel inputs, or a system reference voltage. They are CMOS inputs, so they will not load down any nodes too much.

    If this is not a critical application, you can just tie one input to GND and one to VCC (through a 1k resistor). This technically violates the input voltage range specification, but will not cause damage. I would not expect this to cause any issues with the operating comparator, but it is up to you if you want to do that as if it did cause any "oddities" in the operating comparator, it would not be covered under TI warranty due to the violated spec.



  • 0 in reply to Paul Grohe
    TI__Mastermind 23405 points

    There has not been any new input on this post in a while, so it will be closed.

    If you have additional questions, please feel free to reply or open a new post.

    thanks

    Chuck