TL F 10180
DM74LS197
Presettable
Binary
Counters
February 1992
DM74LS197 Presettable Binary Counters
General Description
The 'LS197 ripple counter contains divide-by-two and di-
vide-by-eight sections which can be combined to form a
modulo-16 binary counter State changes are initiated by
the falling edge of the clock The 'LS197 has a Master Re-
set (MR) input which overrides all other inputs and asyn-
chronously forces all outputs LOW A Parallel Load input
(PL) overrides clocked operations and asynchronously
loads the data on the Parallel Data inputs (P
n
) into the flip-
flops This preset feature makes the circuit usable as a pro-
grammable counter The circuit can also be used as a 4-bit
latch loading data from the Parallel Data inputs when PL is
LOW and storing the data when PL is HIGH For detail spec-
ifications and functional description please refer to the
'LS196 data sheet
Features
Y
High counting rates
Typically 70 MHz
Y
Asynchronous preset
Y
Asynchronous master reset
Connection Diagram
Dual-In-Line Package
TL F 10180 1
Order Number DM74LS197M or DM74LS197N
See NS Package Number M14A or N14A
Pin Names
Description
CP0
d
2 Section Clock Input
(Active Falling Edge)
CP1
d
8 Section Clock Input
(Active Falling Edge)
MR
Asynchronous Master Reset Input
(Active LOW)
P0 P3
Parallel Data Inputs
PL
Asynchronous Parallel Load Input
(Active LOW)
Q0
d
2 Section Output
Q1 Q3
d
8 Section Outputs
Q0 output is guaranteed to drive the full rated fan-out plus the CP1 input
Mode Select Table
Inputs
Response
MR
PL
CP
L
X
X
Qn Forced LOW
H
L
X
Pn
x
Qn
H
H
K
Count Up
H
e
HIGH Voltage Level
L
e
LOW Voltage Level
X
e
Immaterial
C1995 National Semiconductor Corporation
RRD-B30M105 Printed in U S A
Absolute Maximum Ratings
(Note)
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
Supply Voltage
7V
Input Voltage
7V
Operating Free Air Temperature Range
DM74LS
0 C to
a
70 C
Storage Temperature Range
b
65 C to
a
150 C
Note
The ``Absolute Maximum Ratings'' are those values
beyond which the safety of the device cannot be guaran-
teed The device should not be operated at these limits The
parametric values defined in the ``Electrical Characteristics''
table are not guaranteed at the absolute maximum ratings
The ``Recommended Operating Conditions'' table will define
the conditions for actual device operation
Recommended Operating Conditions
Symbol
Parameter
DM74LS197
Units
Min
Nom
Max
V
CC
Supply Voltage
4 75
5
5 25
V
V
IH
High Level Input Voltage
2
V
V
IL
Low Level Input Voltage
0 8
V
I
OH
High Level Output Voltage
b
0 4
mA
I
OL
Low Level Output Current
8
mA
T
A
Free Air Operating Temperature
0
70
C
Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
(Note 1)
V
I
Input Clamp Voltage
V
CC
e
Min I
I
e b
18 mA
b
1 5
V
V
OH
High Level Output Voltage
V
CC
e
Min I
OH
e
Max
2 7
3 4
V
V
IL
e
Max
V
OL
Low Level Output Voltage
V
CC
e
Min I
OL
e
Max
0 35
0 5
V
IH
e
Min
V
I
OL
e
4 mA V
CC
e
Min
0 25
0 4
I
I
Input Current
Max
V
CC
e
Max V
I
e
7V
0 1
mA
Input Voltage
I
IH
High Level Input Current
V
CC
e
Max V
I
e
2 7V
20
m
A
I
IL
Low Level Input Current
V
CC
e
Max V
I
e
0 4V
b
0 4
mA
I
OS
Short Circuit Output Current
V
CC
e
Max (Note 2)
b
20
b
100
mA
I
CC
Supply Current
V
CC
e
Max
27
mA
Note 1
All typicals are at V
CC
e
5V T
A
e
25 C
Note 2
Not more than one output should be shorted at a time and the duration should not exceed one second
2
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