Digital Electronics
In digital circuits, a high impedance (also known as hi-Z, tri-stated, or floating) output is not being driven to any defined logic level by the output circuit. The signal is neither driven to a logical high nor low level; this third condition leads to the description "tri-stated". Such a signal can be seen as an open circuit (or "floating" wire) because connecting it to a low impedance circuit will not affect that circuit; it will instead itself be pulled to the same voltage as the actively driven output. The combined input/output pins found on many ICs are actually tri-state capable outputs which have been internally connected to inputs. This is the basis for bus-systems in computers, among many other uses.
The high-impedance state of a given node in a circuit cannot be verified by a voltage measurement alone. A pull-up resistor can be used to try to pull the wire to high and low voltage levels. If the node is not in a high-impedance state, extra current from the resistor will not significantly affect its voltage level.
Read more about this topic: High Impedance
Famous quotes containing the word electronics:
“We live in a highly industrialized society and every member of the Black nation must be as academically and technologically developed as possible. To wage a revolution, we need competent teachers, doctors, nurses, electronics experts, chemists, biologists, physicists, political scientists, and so on and so forth. Black women sitting at home reading bedtime stories to their children are just not going to make it.”
—Frances Beale, African American feminist and civil rights activist. The Black Woman, ch. 14 (1970)