54LS168 Synchronous Bi-Directional BCD Decade Counter
June 1989
54LS168 Synchronous Bi-Directional
BCD Decade Counter
General Description
The 54LS168 is a fully synchronous 4-state up down coun-
ter featuring a preset capability for programmable operation
carry lookahead for easy cascading and a U D input to con-
trol the direction of counting It counts in the BCD (8421)
sequence and all state changes whether in counting or par-
allel loading are initiated by the LOW-to-HIGH transition of
the clock
Connection Diagram
Dual-In-Line Package
Logic Symbol
TL F 10207 鈥?1
TL F 10207 鈥?2
Order Number 54LS168DMQB
54LS168FMQB or 54LS168LMQB
See NS Package Number
E20A J16A or W16A
V
CC
e
Pin 16
GND
e
Pin 8
Pin Names
CEP
CET
CP
P0鈥揚(yáng)3
PE
U D
Q0鈥換3
TC
Description
Count Enable Parallel Input (Active LOW)
Count Enable Trickle Input (Active LOW)
Clock Pulse Input (Active Rising Edge)
Parallel Data Inputs
Parallel Enable Input (Active LOW)
Up-Down Count Control Input
Flip-Flop Outputs
Terminal Count Output (Active LOW)
C
1995 National Semiconductor Corporation
TL F 10207
RRD-B30M105 Printed in U S A