描述 Description

The HD74HC299 features multiplexed inputs/outputs to achieve full 8-bit data handling in a single 20-pin package. Due to the large output drive capability and 3-state feature, this device is ideally suited for interfacing with bus lines in a bus oriented system. Two function select inputs and two output control inputs are used to choose the mode of operation as listed in the function table. Synchronous parallel loading is accomplished by taking both function select lines S0 and S1 high. This places the 3-state outputs in a high impedance state, which permits data applied to the input/output lines to be clocked into the register. Reading out of the register can be done while the outputs are enabled in any mode. A direct overriding clear input is provided to clear the register whether the outputs are enabled or disabled.

特性 Features

? High Speed Operation

? High Output Current: Fanout of 15 LSTTL Loads

? Wide Operating Voltage: VCC = 2 to 6 V

? Low Input Current: 1 μA max

? Low Quiescent Supply Current: ICC (static) = 4 μA max (Ta = 25°C)