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SN74AVC16245: unused input and output pin

Yoonsun Kim
Expert 1860 points
Part Number: SN74AVC16245
Other Parts Discussed in Thread: SN74AVC16T245

Hi,

I read " Tie any unused input and output ports directly to ground." on page 16 datasheet.

When I tie unused output pin to ground, isn't it hamful to device?

Just tying unused input pin to GND is not enough?

Regards,

Yoonsun

  • +1
    Guru 317490 points

    Page 16 is the TSSOP package outline. I do not find that sentence. What datasheet are you looking at?

    Anyway, all pins can be both input and output. If a pin is always an output (i.e., DIR and /OE never disable it), then it can be left open.

  • 0 in reply to Clemens Ladisch
    Expert 1860 points

    The datasheet version I read is ' SCES551E –FEBRUARY 2004–REVISED NOVEMBER 2015'

    You mean 

    that unused input pin should be tied to ground when DIR is fixed or

    that all unused pin should be tied to ground when DIR can be changed. 

  • +1 in reply to Yoonsun Kim
    Guru 317490 points

    SCES551 is the datasheet of the SN74AVC16T245, not the SN74AVC16245. But the voltage translation makes no difference for this question.

    When an unused pin might be configued as input with DIR, or disabled with /OE, then it should be tied to GND. The only case when an unused pin can be left open is when it is always an active output. Anyway, tying a low output to GND does not hurt, so the simplest solution is to do this for all unused pins.