HD74HC678

HD74HC678 16-bit Address Comparator Description The HD74HC678 address comparator simplifies addressing of memory boards and/or other peripheral devices. The four P inputs are normally hard wired with a preprogrammed address. An internal decoder determines what input information applied to the 16 A inputs must be low or high to cause a low state at the output (Y). For example, a positive-logic bit combination of 0111 (decimal 7) at the P input determines that inputs A1 through A7 must be low and that inputs A8 through A16 must be high to cause the output to go low. Equality of the address applied at the A inputs to the preprogrammed address is indicated by the output being low. The HD74HC678 features a transparent latch and a latch enabled input (C). When C is high, the device is in the transparent mode. When C is low, the previous logic state of Y is latched. Features High Speed Operation High Output Current: Fanout of 10 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) HD74HC678 Function Table Inputs C H H H H H H H H H H H H H H H H H L P3 P2 P1 P0 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 Output Y L L L L L L L L H H H H H H H H L L L L H H H H L L L L H H H H L L H H L L H H L L H H L L H H L H L H L H L H L H L H L H L H H L L L L L L L L L L L L L L L H H L L L L L L L L L L L L L L H H H L L L L L L L L L L L L L H H H H L L L L L L L L L L L L H H ...