NSC DM54191MW8 Datasheet

TL/F/6562

54191/DM54191/DM74191 Synchronous Up/Down 4-Bit Binary Counter with Mode Control

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 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.

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.

Connection Diagram

Dual-In-Line Package

TL/F/6562– 1

Order Number 54191DMQB, 54191FMQB,

DM54191J, DM54191W or DM74191N

See NS Package Number J16A, N16E or W16A

C

1995 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 5.5V

Operating Free Air Temperature Range

DM54 and 54

b

55§Ctoa125§C

DM74 0

§

Ctoa70§C

Storage Temperature Range

b

65§Ctoa150§C

Note:

The ‘‘Absolute Maximum Ratings’’ are those values
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.

Recommended Operating Conditions

Symbol Parameter

DM54191 DM74191

Units

Min Nom Max Min Nom Max

V

CC

Supply Voltage 4.5 5 5.5 4.75 5 5.25 V

V

IH

High Level Input Voltage 2 2 V

V

IL

Low Level Input Voltage 0.8 0.8 V

I

OH

High Level Output Current

b

0.8

b

0.8 mA

I

OL

Low Level Output Current 16 16 mA

f

CLK

Clock Frequency (Note 4) 0 20 0 20 MHz

t

W

Pulse Width Clock 25 25

ns

(Note 4)

Load 35 35

t

SU

Data Setup Time (Note 4) 28 28 ns

t

H

Hold Time (Note 4) 0 0 ns

t

REL

Load Release Time (Note 4) 30 30 ns

T

A

Free Air Operating Temperature

b

55 125 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

eb

12 mA

b

1.5 V

V

OH

High Level Output V

CC

e

Min, I

OH

e

Max

2.4 3.4 V

Voltage V

IL

e

Max, V

IH

e

Min

V

OL

Low Level Output V

CC

e

Min, I

OL

e

Max

0.2 0.4 V

Voltage V

IH

e

Min, V

IL

e

Max

I

I

Input Current@Max V

CC

e

Max, V

I

e

5.5V
1mA

Input Voltage

I

IH

High Level Input V

CC

e

Max Enable 120

mA

Current V

I

e

2.4V
Others 40

I

IL

Low Level Input V

CC

e

Max Enable

b

4.8
mA

Current V

I

e

0.4V
Others

b

1.6

I

OS

Short Circuit V

CC

e

Max DM54

b

20

b

65

mA

Output Current (Note 2)

DM74

b

18

b

65

I

CC

Supply Current V

CC

e

Max DM54 65 99

mA

(Note 3)

DM74 65 105

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.

Note 3: I

CC

is measured with all inputs grounded and all outputs open.

Note 4: T

A

e

25§C and V

CC

e

5V.

2