HD74HC299

HD74HC299 8-bit Universal Shift/Storage Register (with 3-state outputs) 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 S 1 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. 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) HD74HC299 Function Table Inputs Function Select Mode Clear Clear L L Hold H H Shift Right Shift Left Load H H H H H S1 X L L X L L H H H S0 L X L X H H L L H Output Control G1† G2† L L L L L L L L X L L L L L L L L X Serial Inputs/Outputs Outputs QH’ L L QH0 QH0 QGn QGn H L h Clock SL SR A/QA B/QB C/QC D/QD E/QE F/QF G/Q G H/QH QA’ X X X L X X X X X X H L X X...