Tri-State Bus Driver Control
Original Publication Date: 1988-Jan-01
Included in the Prior Art Database: 2005-Feb-14
Described is a logic circuit for using data signals to control associated tri-state bus drivers. Tri-state drivers are commonly used to interconnect registers and ports in logic networks. When enabled, the tri-state driver transmits data onto a bus line for transfer to another part of the network. When disabled, the driver's output terminal exhibits a high impedance to eliminate undue loading of any enabled drivers on the bus line. The drivers usually include a transistor output stage without a load impedance. A pull-up resistor is supplied to keep the bus at a high voltage level - the "off" state - when no driver is enabled. A non-inverting driver 4 is shown in Fig. 1 and has an enable input whereby a low signal activates the driver, coupling the input signal to a bus line.