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LP211: LP211

Part Number: LP211
Other Parts Discussed in Thread: TLV7011, TLV7032, LM393

Dear Team,

   Is there a need to add Hysteresis on windows comparator? I saw TI's reference design don't have Hysteresis on windows comparator?

Thanks,

Tony

  • Hi Tony,

    A window comparator is just two comparators sharing a common output. So hysteresis can be added to each channel.

    But it does get complicated depending on the source impedance on the positive inputs, and how the reference voltages are generated, to prevent interaction between the two channels due to the feedback. The typical three-resistor divider string may need to be broken into two separate dividers.

    It may be easier to use a comparator with built-in hysteresis, such as the TLV7011 or TLV7032 series.

  • Hi Paul,

      if we add a external feedback resistor, How big the Hysteresis can I reach? 2V or 3V is okay with LM393?

    Thanks,

    Tony

  • Tony

    In regards to hysteresis levels that are achievable with the LM393, you need to be conscious of the input common mode range.  When the output is a logic high, if you have a large amount of hysteresis, the non-inverting input could be increased outside the common mode range of the LM393.  So when you implement hysteresis, please calculate what voltage is being applied to the non-inverting pin.

    Chuck