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 asynchronous (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 counting. 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 number of clock drivers, etc., required for long parallel words.
June 1989
Two outputs have been made available to perform the cascading 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 accomplish 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 available. Contact a National Semiconductor Sales Office/
Distributor for specifications.
54191/DM54191/DM74191 Synchronous Up/Down 4-Bit Binary Counter with Mode Control
Connection Diagram
Dual-In-Line Package
Order Number 54191DMQB, 54191FMQB,
DM54191J, DM54191W or DM74191N
See NS Package Number J16A, N16E or W16A
C
1995 National Semiconductor CorporationRRD-B30M105/Printed in U. S. A.
TL/F/6562
TL/F/6562– 1
Absolute Maximum Ratings (Note)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage7V
Input Voltage5.5V
Operating Free Air Temperature Range
DM54 and 54
DM740
Storage Temperature Range
b
55§Ctoa125§C
Ctoa70§C
§
b
65§Ctoa150§C
Recommended Operating Conditions
SymbolParameter
V
V
V
I
OH
I
OL
f
t
t
t
t
T
CC
IH
IL
CLK
W
SU
H
REL
A
Supply Voltage4.555.54.7555.25V
High Level Input Voltage22V
Low Level Input Voltage0.80.8V
High Level Output Current
Low Level Output Current1616mA
Clock Frequency (Note 4)020020MHz
Pulse WidthClock2525
(Note 4)
Load3535
Data Setup Time (Note 4)2828ns
Hold Time (Note 4)00ns
Load Release Time (Note 4)3030ns
Free Air Operating Temperature
The ‘‘Absolute Maximum Ratings’’ are those values
Note:
beyond which the safety of the device cannot be guaranteed. 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.
DM54191DM74191
MinNomMaxMinNomMax
b
0.8
b
55125070
b
Units
0.8mA
ns
§
C
Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted)
SymbolParameterConditionsMin
e
V
I
V
OH
V
OL
I
I
I
IH
I
IL
I
OS
I
CC
Note 1: All typicals are at V
Note 2: Not more than one output should be shorted at a time.
Note 3: I
Note 4: T
Input Clamp VoltageV
High Level OutputV
VoltageV
Low Level OutputV
VoltageV
Input Current@MaxV
Input Voltage
High Level InputV
CurrentV
Low Level InputV
CurrentV
Short CircuitV
Output Current(Note 2)
Supply CurrentV
e
e
5V, T
5V.
25§C.
A
CC
is measured with all inputs grounded and all outputs open.
CC
e
A
25§C and V
e
CC
CC
CC
IL
CC
IH
CC
CC
e
I
CC
e
I
CC
CC
(Note 3)
e
e
eb
Min, I
e
Min, I
Max, V
e
Min, I
Min, V
e
Max, V
e
MaxEnable120
2.4V
e
MaxEnable
0.4V
e
MaxDM54
e
MaxDM546599
12 mA
I
e
Max
OH
e
Min
IH
e
Max
OL
e
Max
IL
e
5.5V
I
Others40
Others
b
DM74
b
DM7465105
2
2.43.4V
20
18
Typ
(Note 1)
MaxUnits
b
1.5V
0.20.4V
1mA
b
4.8
b
1.6
b
65
b
65
mA
mA
mA
mA
Switching Characteristics at V
SymbolParameter
f
MAX
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
Maximum Clock Frequency20MHz
Propagation Delay TimeLoad to
Low to High Level OutputAny Q
Propagation Delay TimeLoad to
High to Low Level OutputAny Q
Propagation Delay TimeData to
Low to High Level OutputAny Q
Propagation Delay TimeData to
High to Low Level OutputAny Q
Propagation Delay TimeClock to
Low to High Level OutputRipple Carry
Propagation Delay TimeClock to
High to Low Level OutputRipple Carry
Propagation Delay TimeClock to
Low to High Level OutputAny Q
Propagation Delay TimeClock to
High to Low Level OutputAny Q
Propagation Delay TimeClock to
Low to High Level OutputMax/Min
Propagation Delay TimeClock to
High to Low Level OutputMax/Min
Propagation Delay TimeDown/Up to
Low to High Level OutputRipple Carry
Propagation Delay TimeDown/Up to
High to Low Level OutputRipple Carry
Propagation Delay TimeDown/Up to
Low to High Level OutputMax/Min
Propagation Delay TimeDown/Up to
High to Low Level OutputMax/Min
Propagation Delay TimeEnable G to
Low to High Level OutputRipple Carry
Propagation Delay TimeEnable G to
High to Low Level OutputRipple Carry
CC
e
5V and T
e
A
From (Input)R
To (Output)
25§C (See Section 1 for Test Waveforms and Output Load)
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54191/DM54191/DM74191 Synchronous Up/Down 4-Bit Binary Counter with Mode Control
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