NSC DM74LS461J Octal counter Datasheet

DM54LS461/DM74LS461 Octal Counter
General Description
The LS461 is an 8-bit synchronous counter with parallel
load, clear, and hold capability. Two function select inputs
(I0, I1) provide one of four operations which occur synchronously on the rising edge of the clock (CK).
The LOAD operation loads the inputs (D7 – D0) into the output register (Q7 – Q0). The CLEAR operation resets the output register to all LOWs. The HOLD operation holds the
previous value regardless of clock transitions. The INCREMENT operation adds one to the output register when the
carry-in input is TRUE (CI e LOW), otherwise the operation
is a HOLD. The carry-out (CO) is TRUE (CO e LOW) when
the output register (Q7 – Q0) is all HIGHs, otherwise FALSE
(CO e HIGH).
The output register (Q7 – Q0) 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 standards.
Two or more LS461 octal counters may be cascaded to
provide larger counters. The operation codes were chosen
such that when I1 is HIGH, I0 may be used to select between LOAD and INCREMENT as in a program counter
(JUMP/INCREMENT).
Connection Diagram
Standard Test Load
Features/Benefits
Y
Y
Y
Y
Y
Y
Y
Octal counter for microprogram-counter, DMA controller
and general purpose counting applications
8 bits match byte boundaries
Bus-structured pinout
24-pin Skinny Dip saves space
TRI-STATEÉ outputs drive bus lines
Low current PNP inputs reduce loading
Expandable in 8-bit increments
Top View
TL/L/8334 – 2
TL/L/8334 – 1
Order Number DM54LS461J,
DM74LS461J or DM74LS461N
See NS Package Number J24F or N24C
Function Table
OE
CK
I1
I0
CI
D7 – D0
Q7 – Q0
Operation
H
L
L
L
L
L
X
X
L
L
H
H
H
X
L
H
L
H
H
X
X
X
X
H
L
X
X
X
D
X
X
Z
L
Q
D
Q
Q plus 1
HI-Z
CLEAR
HOLD
LOAD
HOLD
INCREMENT
u
u
u
u
u
TRI-STATEÉ is a registered trademark of National Semiconductor Corp.
C1995 National Semiconductor Corporation
TL/L/8334
RRD-B30M115/Printed in U. S. A.
DM54LS461/DM74LS461 Octal Counter
July 1989
Absolute Maximum Ratings
Off-State Output Voltage
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage VCC
5.5V
Storage Temperature
b 65§ C to a 150§ C
7V
Input Voltage
5.5V
Operating Conditions
Symbol
Military
Parameter
Min
Typ
4.5
5
VCC
Supply Voltage
TA
Operating Free-Air Temperature
tW
Width of Clock
tSU
Set Up Time
60
th
Hold Time
0
Commercial
b 55
Units
Max
Min
Typ
Max
5.5
4.75
5
5.25
V
125*
0
75
§C
Low
40
35
High
30
25
ns
50
b 15
ns
0
b 15
*Case Temperature
Electrical Characteristics Over Operating Conditions
Symbol
Parameter
Test Conditions
Min
Typ ²
Max
Low-Level Input Voltage
VIH
High-Level Input Voltage
VIC
Input Clamp Voltage
VCC e MIN
II eb18 mA
b 1.5
V
IIL
Low-Level Input Current
VCC e MAX
VI e 0.4V
b 0.25
mA
IIH
High-Level Input Current
VCC e MAX
VI e 2.4V
25
mA
II
Maximum Input Current
VCC e MAX
VI e 5.5V
1
mA
VOL
Low-Level Output Voltage
0.5
V
VOH
High-Level Output Voltage
0.8
Units
VIL
2
VCC e MIN
VIL e 0.8V
VIH e 2V
VCC e MIN
VIL e 0.8V
VIH e 2V
Off-State Output Current
VCC e MAX
VIL e 0.8V
VIH e 2V
IOS
Output Short-Circuit Current*
VCC e 5.0V
ICC
Supply Current
VCC e MAX
IOZL
IOZH
MIL
IOL e 12 mA
COM
IOL e 24 mA
MIL
IOH eb2 mA
COM
V
V
2.4
V
IOH eb3.2 mA
VO e 0.4V
b 100
VO e 2.4V
VCC e 0V
b 30
120
mA
100
mA
b 130
mA
180
mA
*No more than one output should be shorted at a time and duration of the short-circuit should not exceed one second
² All typical values are at VCC e 5V, TA e 25§ C.
Switching Characteristics Over Operating Conditions
Symbol
Parameter
fMAX
Maximum Clock Frequency
tPD
CBI to CBO Delay
tPD
Clock to Q
tPD
Clock to CO
tPZX
Output Enable Delay
tPXZ
Output Disable Delay
Test Conditions
(See Test Load)
Military
Min
Commercial
Typ
Max
35
CL e 50 pF
R1 e 200 X
R2 e 390 X
2
Units
Typ
Max
60
35
50
ns
20
35
20
30
ns
55
95
55
80
ns
35
55
35
45
ns
35
55
35
45
ns
10.5
Min
12.5
MHz
Logic Diagram
LS461
TL/L/8334 – 3
3
DM54LS461/DM74LS461 Octal Counter
Physical Dimensions inches (millimeters)
24-Pin Narrow Ceramic Dual-In-Line Package (J)
Order Number DM54LS461J or DM74LS461J
NS Package J24F
LIFE SUPPORT POLICY
24-Pin Narrow Plastic Dual-In-Line Package (N)
Order Number DM74LS461N
NS Package N24C
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