Thursday, July 17, 2008

Tri-State Buffer 101

Tri-State Buffers are a common form of logic for many bus applications. The tri-state obviously stands for three states, which represent the 3 possible out put states: high, low and floating.
  • High is logic 1
  • Low is logic 0
  • Floating is not controlled by the buffer (Z)

During the floating state the Output is not being controlled in anyway by the input signal.

There are two inputs and one output.
  • Input Signal - is the logic level that is forwarded to the Output signal
  • Input Control Signal - determines if the Output Signal is equal to the Input Signal or if the Output Signal is floating

  • If the Input Control Signal is logic level High (1) the Output Signal is equal to the Input Signal
  • If the Input Control Signal is logic level Low (0) the Output Signal is in a floating state




at

1 comment:

  1. MattAugust 12, 2008 at 1:06 AM

    The coolest part about Tri-state buffers for me is when they're used to interface to external chip-based memory. They can switch pins from input to output on the same set of wires as another device, thereby creating a handy little "bus".

    This is probably the single coolest thing I ever learned from the NYC hackfests!

    ReplyDelete