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UCC27533: what's the 'x' meaning in true table?

Part Number: UCC27533
Other Parts Discussed in Thread: UCC27536


in datasheet true table, there are 'float' and 'x'.

i think float represent 'leave this pin unconnected', right?

what's the 'x' meaning?

  • Hi, 

    Yes, FLOAT means if you leave the pin unconnected to anything. 

    And, “X” is shorthand for “don’t care.” Basically, the other pin has priority over the one with the X in it. 

    If this answered your question, please press the Green button, otherwise let us know if you have further questions. 

    Best regards,


  • Hi, Don,

    As you explained "X" is "don't care", i am still confused on 'X' in the table below. 

    For UCC27536DBV, while "EN PIN" is H, if i set "IN-/IN+" to be H, "OUT PIN" will be L; set "IN-/IN+" to be L, "OUT PIN" will be H,

    The setting of "EN PIN H, IN-/IN+ X" is contradict with the two lines above.

  • Hello,

    UCC27536 is an inverting driver meaning that when IN- is high, the OUT pins will go low.

    The X in the logic truth table simply means that the pin is in floating condition during which, IN- is internally pulled high and since it is inverting driver, OUT is inverted when EN high and IN- pulled high.

    Hope this clarifies.