DM54LS469 DM74LS469 8-Bit Up Down Counter
July 1989
DM54LS469 DM74LS469 8-Bit Up Down Counter
General Description
The 鈥楲S469 is an 8-bit synchronous up down counter with
parallel load and hold capability Three function-select in-
puts (LD UD CBI) provide one of four operations which
occur synchronously on the rising edge of the clock (CK)
The LOAD operation loads the inputs (D
7
鈥揇
0
) into the out-
put register (Q
7
鈥換
0
) The HOLD operation holds the previ-
ous value regardless of clock transitions The INCREMENT
operation adds one to the output register when the carry-in
input is TRUE (CBI
e
LOW) otherwise the operation is a
HOLD The carry-out (CBO) is TRUE (CBO
e
LOW) when
the output register (Q
7
鈥換
0
) is all HIGHs otherwise FALSE
(CBO
e
HIGH) The DECREMENT operation subtracts one
from the output register when the borrow-in input is TRUE
(CBI
e
LOW) otherwise the operation is a HOLD The bor-
row-out (CBO) is TRUE (CBO
e
LOW) when the output reg-
ister (Q
7
鈥換
0
) is all LOWs otherwise FALSE (CBO
e
HIGH)
The output register (Q
7
鈥換
0
) is enabled when OE is LOW
and disabled (HI-Z) when OE is HIGH The output drivers
will sink the 24 mA required for many bus-interface stan-
dards Two or more 鈥楲S469 octal up down counters may be
cascaded to provide larger counters
Features Benefits
Y
Y
Y
Y
Y
Y
Y
8-bit up down counter for microprogram-counter DMA
controller and general-purpose counting applications
8 bits matches byte boundaries
Bus-structured pinout
24-pin SKINNYDIP saves space
TRI-STATE outputs drive bus lines
Low current PNP inputs reduce loading
Expandable in 8-bit increments
Connection Diagram
Top View
Standard Test Load
TL L 8333 鈥?
TL L 8333 鈥?
Order Number DM54LS469J
DM74LS469J or DM74LS469N
See NS Package Number J24F or N24C
Function Table
OE CK LD UD CBI D7 鈥?D0
H
L
L
L
L
L
X
Q7 鈥?Q0
Operation
X
L
H
H
H
H
X
X
L
L
H
H
X
X
H
L
H
L
X
D
X
X
X
X
Z
HI-Z
D
LOAD
Q
HOLD
Q plus 1 INCREMENT
Q
HOLD
Q minus 1 DECREMENT
u
u
u
u
u
TRI-STATE is a registered trademark of National Semiconductor Corp
C
1995 National Semiconductor Corporation
TL L 8333
RRD-B30M115 Printed in U S A
1
2
3
4
