Why are tristate buffers used in circuit designing?

Discussion in 'General Electronics Chat' started by sharath_412, May 22, 2007.

  1. sharath_412

    Thread Starter Active Member

    May 7, 2007

    I want to know why the tristate buffers are used in circuit designing.
    One reason is if there is common bus to many IC's.

    1. Are they used if a component cant drive the load.

    I want to know if there are any other reasons for using tristate buffers.
  2. Papabravo


    Feb 24, 2006
  3. cumesoftware

    Senior Member

    Apr 27, 2007
    Tristate buffers are used when more than one IC is capable of producing output in a common bus. Tristate buffers are used so the lines connected at the bus can serve as both input and output. This way one IC will produce its output while others are "listening" or idle.
    Normally they are used in computer systems. For example, a 8085 CPU requests the memory contents from a determined chip (the chip is selected throught the most significant bits of the address bus). Therefore, only this chip will use the data bus to produce output. The other memory chips will be idle.

    P.S.: The tristate buffers are inside each chip.