MM54HC646 MM74HC646 Non-Inverting Octal Bus Transceiver Registers
MM54HC648 MM74HC648 Inverting Octal Bus Transceiver Registers
January 1988
MM54HC646 MM74HC646 Non-Inverting
Octal Bus Transceiver Registers
MM54HC648 MM74HC648
Inverting Octal Bus Transceiver Registers
General Description
These transceivers utilize advanced silicon-gate CMOS
technology and contain two sets of TRI-STATE outputs
two sets of D-type flip-flops and control circuitry designed
for high speed multiplexed transmission of data
Six control inputs enable this device to be used as a latched
transceiver unlatched transceiver or a combination of both
As a latched transceiver data from one bus is stored for
later retrieval by the other bus Alternately real time bus
data (unlatched) may be directly transferred from one bus to
another
Circuit operation is determined by the G DIR CAB CBA
SAB SBA control inputs The enable input G controls
whether any bus outputs are enabled The direction control
DIR determines which bus is enabled and hence the direc-
tion data flows The SAB SBA inputs control whether the
latched data (stored in D type flip flops) or the bus data
(from other bus input pins) is transferred Each set of flip-
flops has its own clock CAB and CBA for storing data Data
is latched on the rising edge of the clock
Each output can drive up to 15 low power Schottky TTL
loads These devices are functionally and pin compatible to
their LS-TTL counterparts All inputs are protected from
damage due to static discharge by diodes to V
CC
and
ground
Features
Y
Y
Y
Y
Y
Y
Typical propagation delay 14 ns
TRI-STATE outputs
Bidirectional communication
Wide power supply range 2 鈥?6V
Low quiescent supply current 160
mA
maximum (74HC)
High output current 6 mA (74HC)
Connection Diagram
Dual-In-Line Package
Order Number MM54HC646 648 or
MM74HC646 648
TL F 5345 鈥?2
TL F 5345 鈥?1
Real-Time Transfer
Bus B to Bus A
Real-Time Transfer
Bus A to Bus B
Storage from
A B or A and B
Transfer Stored Data
to A or B
TRI-STATE is a registered trademark of National Semiconductor Corp
C
1995 National Semiconductor Corporation
TL F 5345
RRD-B30M105 Printed in U S A
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