Octal bus transceiver, non-inverting (open collector)
• High-impedance NPN base inputs for reduced loading
(20µA in High and Low states)
• Octal bidirectional bus interface
• Open collector outputs sink 64mA
The 74F621 is an octal transceiver featuring non-inverting open
collector bus-compatible outputs in both send and receive
directions. The outputs are capable of sinking 64mA, providing very
good capacitive drive characteristics.
This octal bus transceiver is designed for asynchronous two-way
communication between data buses. The control function
implementation allows for maximum flexibility in timing.
The device allows data transmission from the A bus to the B bus or
from the B bus to the A bus, depending upon the logic levels at the
Enable inputs (OEBA and OEAB). The Enable inputs can be used to
disable the device so that the buses are effectively isolated.
The dual-enable configuration gives the 74F621 the capability to
store data by the simultaneous enabling of OEBA and OEAB. Each
output reinforces its input in this transceiver configuration. Thus,
when both control inputs are enabled and all other data sources to
the two sets of the bus lines are at high impedance, both sets of bus
lines (16 in all) will remain in their last states.
TYPICAL SUPPLY CURRENT
VCC = 5V ±10%,
Tamb = 0°C to +70°C
20-pin plastic DIP
20-pin plastic SOL
INPUT AND OUTPUT LOADING AND FAN-OUT TABLE
A0 - A7, B0 - B7
Output Enable inputs
A0 - A7
B0 - B7
NOTE: One (1.0) FAST unit load is defined as: 20µA in the High state and 0.6mA in the Low state. OC = Open Collector.
1996 Jan 05
2 853–0380 16185