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TLC556: Unused pins

Elisha Tarroza71
Expert 3700 points
Part Number: TLC556
Other Parts Discussed in Thread: TLC555

Hello, 

Datasheet mentions that unused input pins should be connected to "appropriate" logic levels. May I know if these are the voltages at the electrical characteristics?
Since there are varying voltage levels, will it be alright to just connect the input pins to ground?

For the out and discharge pins, will it be alright to leave them floating?

Thank you

  • 0
    TI__Guru**** 164406 points

    Elisha,

    That advice applies for timers that are being used but not all features are needed. When reset pin is not needed, tie it to VDD pin. Control pin is an input/output pin that can be left floating or connected to a capacitor to ground, for noise filtering. In some weird case when trigger wasn't needed it can be tied to VDD. In odd case when threshold wasn't needed it can be tied to ground.

    If the second timer wasn't needed then using TLC555 makes more sense. If TLC556 was used anyway, just tie RESET to ground, and tie TRIG and THRES to either ground or VDD. Control and output can be unconnected. Discharge can be open or connected to ground.