Tristate Buffer Output if Input is High-Z?

Jeff> If a tristate buffer is enabled by its control line, but the Jeff> input to the buffer is at high-Z is there a typical output? Not necessarily. Hi-Z means the source of your input is not driving it. That means it is equivalent to an unconnected input. Does your device have an internal pull-up or pull-down? If yes, then an unconnected input is equivalent to a high input, or low input, respectively. If it doesn't have a pull-up or pull-down, then you have a floating input, which means the behavior is undefined. It may be bouncing on and off due to noise; it may end up behaving like low in one chip and high in another of the same type, based on process variations; it may change from one to the other as temperature changes. Oh yes, and if it's CMOS it will probably draw more current than you expect because you're not driving it to a well defined high or low state. You should always have a defined input signal for all inputs. That can be an internal pull-up/down; it can be an external one; or it can be that you arrange for it always to be explicitly driven (always exactly one source *not* in high-Z mode). paul