Octal 3-State Bus Transceivers
and D Flip-Flops
High-Performance Silicon-Gate CMOS
The IN74HC651A is identical in pinout to the LS/ALS651. The
device inputs are compatible with standard CMOS outputs; with pullup
resistors, they are compatible with LS/ALSTTL outputs.
These devices consist of bus transceiver circuits, D-type flip-flop, and
control circuitry arranged for multiplex transmission of data directly from
the data bus or from the internal storage registers. Direction and Output
Enable are provided to select the read-time or stored data function. Data
on the A or B Data bus, or both, can be stored in the internal D flip-flops
by low-to-high transitions at the appropriate clock pins (A-to-B Clock or
B-to-A Clock) regardless of the select or enable or enable control pins.
When A-to-B Source and B-to-A Source are in the real-time transfer
mode, it is also possible to store data without using the internal D-type
flip-flops by simulta-neously enabling Direction and Output Enable. In
this configuration each output reinforces its input. Thus, when all other
data sources to the two sets of bus lines are at high impedance, each set of
bus lines will remain at its last state.
The IN74HC651A has inverted outputs.
• Outputs Directly Interface to CMOS, NMOS, and TTL
• Operating Voltage Range: 2.0 to 6.0 V
• Low Input Current: 1.0 µA
• High Noise Immunity Characteristic of CMOS Devices
TA = -55° to 125° C for all packages