HD74HC678 Datasheet, PDF (1/8 Pages) Hitachi Semiconductor – 16-bit Address Comparator

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: V_CC = 2 to 6 V
• Low Input Current: 1 µA max
• Low Quiescent Supply Current: I_CC (static) = 4 µA max (Ta = 25°C)