TL/F/9580
54F/74F646
#
74F646B
#
54F/74F648
Octal
Transceiver/Register
with
TRI-STATE
Outputs
December 1994
54F/74F646 # 74F646B # 54F/74F648
Octal Transceiver/Register with TRI-STATE Outputs
General Description
These devices consist of bus transceiver circuits with TRI-
STATE, D-type flip-flops, and control circuitry arranged for
multiplexed transmission of data directly from the input bus
or from the internal registers. Data on the A or B bus will be
clocked into the registers as the appropriate clock pin goes
to a high logic level. Control G and direction pins are provid-
ed to control the transceiver function. In the transceiver
mode, data present at the high impedance port may be
stored in either the A or the B register or in both. The select
controls can multiplex stored and real-time (transparent
mode) data. The direction control determines which bus will
receive data when the enable control G is Active LOW. In
the isolation mode (control G HIGH), A data may be stored
in the B register and/or B data may be stored in the A regis-
ter.
Features
Y
Independent registers for A and B buses
Y
Multiplexed real-time and stored data
Y
’F648 has inverting data paths
Y
’F646/’F646B have non-inverting data paths
Y
’F646B is a faster version of the ’F646
Y
TRI-STATE outputs
Y
300 mil slim DIP
Y
Guaranteed 4000V minimum ESD protection
Commercial Military
Package
Package Description
Number
74F646SPC N24C 24-Lead (0.300 Wide) Molded Dual-In-Line
54F646DM (Note 2) J24F 24-Lead (0.300 Wide) Ceramic Dual-In-Line
74F646SC (Note 1) M24B 24-Lead (0.300 Wide) Molded Small Outline, JEDEC
74F646MSA (Note 1) MSA24 24-Lead Molded Shrink Small Outline, EIAJ, Type II
54F646FM (Note 2) W24C 24-Lead Cerpack
54F646LM (Note 2) E28A 28-Lead Ceramic Leadless Chip Carrier, Type C
74F646BSPC N24C 24-Lead (0.300 Wide) Molded Dual-In-Line
74F646BSC (Note 1) M24B 24-Lead (0.300 Wide) Molded Small Outline, JEDEC
74F648SPC N24C 24-Lead (0.300 Wide) Molded Dual-In-Line
54F648SDM (Note 2) J24F 24-Lead (0.300 Wide) Ceramic Dual-In-Line
74F648SC (Note 1) M24B 24-Lead (0.300 Wide) Molded Small Outline, JEDEC
54F648FM (Note 2) W24C 24-Lead Cerpack
54F648LM (Note 2) E28A 24-Lead Ceramic Leadless Chip Carrier, Type C
Note 1: Devices also available in 13 reel. Use suffix e SCX.
Note 2: Military grade device with environmental and burn-in processing. Use suffix e DMQB, FMQB and LMQB.
Logic Symbols
’F646/’F646B
TL/F/9580–1
’F648
TL/F/9580–7
TRI-STATE is a registered trademark of National Semiconductor Corporation.
C
1995 National Semiconductor Corporation RRD-B30M75/Printed in U. S. A.