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National Semiconductor Electronic Components Datasheet


74191

Synchronous Up/Down 4-Bit Binary Counter with Mode Control



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74191 pdf
June 1989
54191 DM54191 DM74191 Synchronous Up Down
4-Bit Binary Counter with Mode Control
General Description
This circuit is a synchronous reversible up down counter
The 191 is a 4-bit binary counter Synchronous operation is
provided by having all flip-flops clocked simultaneously so
that the outputs change simultaneously when so instructed
by the steering logic This mode of operation eliminates the
output counting spikes normally associated with asynchro-
nous (ripple clock) counters
The outputs of the four master-slave flip-flops are triggered
on a low-to-high level transition of the clock input if the
enable input is low A high at the enable input inhibits count-
ing Level changes at either the enable input or the down
up input should be made only when the clock input is high
The direction of the count is determined by the level of the
down up input When low the counter counts up and when
high it counts down
This counter is fully programmable that is the outputs may
be preset to either level by placing a low on the load input
and entering the desired data at the data inputs The output
will change independent of the level of the clock input This
feature allows the counters to be used as modulo-N dividers
by simply modifying the count length with the preset inputs
The clock down up and load inputs are buffered to lower
the drive requirement which significantly reduces the num-
ber of clock drivers etc required for long parallel words
Two outputs have been made available to perform the cas-
cading function ripple clock and maximum minimum count
The latter output produces a high-level output pulse with a
duration approximately equal to one complete cycle of the
clock when the counter overflows or underflows The ripple
clock output produces a low-level output pulse equal in
width to the low-level portion of the clock input when an
overflow or underflow condition exists The counters can be
easily cascaded by feeding the ripple clock output to the
enable input of the succeeding counter if parallel clocking is
used or to the clock input if parallel enabling is used The
maximum minimum count output can be used to accom-
plish look-ahead for high-speed operation
Features
Y Single down up count control line
Y Count enable control input
Y Ripple clock output for cascading
Y Asynchronously presettable with load control
Y Parallel outputs
Y Cascadable for n-bit applications
Y Alternate Military Aerospace device (54191) is avail-
able Contact a National Semiconductor Sales Office
Distributor for specifications
Connection Diagram
Dual-In-Line Package
Order Number 54191DMQB 54191FMQB
DM54191J DM54191W or DM74191N
See NS Package Number J16A N16E or W16A
TL F 6562 – 1
C1995 National Semiconductor Corporation TL F 6562
RRD-B30M105 Printed in U S A



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74191 pdf
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
5 5V
Operating Free Air Temperature Range
DM54 and 54
b55 C to a125 C
DM74
0 C to a70 C
Storage Temperature Range
b65 C to a150 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
VCC
VIH
VIL
IOH
IOL
fCLK
tW
tSU
tH
tREL
TA
Parameter
Supply Voltage
High Level Input Voltage
Low Level Input Voltage
High Level Output Current
Low Level Output Current
Clock Frequency (Note 4)
Pulse Width
(Note 4)
Data Setup Time (Note 4)
Hold Time (Note 4)
Load Release Time (Note 4)
Free Air Operating Temperature
Clock
Load
Min
45
2
0
25
35
28
0
30
b55
DM54191
Nom
5
Max
55
08
b0 8
16
20
125
DM74191
Min Nom Max
4 75 5
5 25
2
08
b0 8
16
0 20
25
35
28
0
30
0 70
Units
V
V
V
mA
mA
MHz
ns
ns
ns
ns
C
Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted)
Symbol
Parameter
Conditions
VI
VOH
VOL
II
Input Clamp Voltage
High Level Output
Voltage
Low Level Output
Voltage
Input Current Max
Input Voltage
VCC e Min II e b12 mA
VCC e Min IOH e Max
VIL e Max VIH e Min
VCC e Min IOL e Max
VIH e Min VIL e Max
VCC e Max VI e 5 5V
IIH
High Level Input
VCC e Max
Enable
Current
VI e 2 4V
Others
IIL
Low Level Input
VCC e Max
Enable
Current
VI e 0 4V
Others
IOS Short Circuit
Output Current
VCC e Max
(Note 2)
DM54
DM74
ICC Supply Current
VCC e Max
(Note 3)
Note 1 All typicals are at VCC e 5V TA e 25 C
Note 2 Not more than one output should be shorted at a time
Note 3 ICC is measured with all inputs grounded and all outputs open
Note 4 TA e 25 C and VCC e 5V
DM54
DM74
Min
24
b20
b18
Typ
(Note 1)
34
02
65
65
Max
b1 5
04
1
120
40
b4 8
b1 6
b65
b65
99
105
Units
V
V
V
mA
mA
mA
mA
mA
2



Part Number 74191
Description Synchronous Up/Down 4-Bit Binary Counter with Mode Control
Maker National Semiconductor - National Semiconductor
Total Page 6 Pages
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