dm74ls190 National Semiconductor Corporation, dm74ls190 Datasheet

dm74ls190

Manufacturer Part Number

dm74ls190

Description

Synchronous 4-bit Up/down Counters With Mode Control

Manufacturer

National Semiconductor Corporation

Datasheet

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C 1995 National Semiconductor Corporation

DM54LS190 DM74LS190 DM54LS191 DM74LS191

Synchronous 4-Bit Up Down Counters with Mode Control

General Description

These circuits are synchronous reversible up down coun-

ters The LS191 is a 4-bit binary counter and the LS190 is a

BCD 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 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

These counters are 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 in-

put 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

Connection Diagram

DM54LS191W DM74LS190M DM74LS191M DM74LS190N or DM74LS191N

TL F 6405

Order Number DM54LS190J DM54LS191J DM54LS190W

J16A M16A N16A or W16A

See NS Package Number

Dual-In-Line-Package

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

Counts 8-4-2-1 BCD or binary

Single down up count control line

Count enable control input

Ripple clock output for cascading

Asynchronously presettable with load control

Parallel outputs

Cascadable for n-bit applications

Average propagation delay 20 ns

Typical clock frequency 25 MHz

Typical power dissipation 100 mW

TL F 6405-1

RRD-B30M105 Printed in U S A

May 1989

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dm74ls190 Summary of contents

Page 1

... Connection Diagram Order Number DM54LS190J DM54LS191J DM54LS190W DM54LS191W DM74LS190M DM74LS191M DM74LS190N or DM74LS191N C 1995 National Semiconductor Corporation TL F 6405 Two outputs have been made available to perform the cas- ...

Page 2

... CC Max Enable e 7V Others Max Enable Others Max Enable Others Max DM54 DM74 20 b Max (Note DM74LS190 LS191 Units Min Nom Max MHz ...

Page 3

Switching Characteristics and (See Section 1 for Test Waveforms and Output Load Symbol Parameter f Maximum Clock MAX Frequency t Propagation Delay Time PLH Low to High ...

Page 4

Logic Diagrams Pin (16 Pin (8) e GND CC LS190 Decade Counters TL F 6405 – ...

Page 5

Logic Diagrams (Continued) LS191 Binary Counters TL F 6405 – Pin (16 Pin (8) e GND CC ...

Page 6

Timing Diagrams Typical Load Count and Inhibit Sequences Typical Load Count and Inhibit Sequences LS190 Decade Counters LS191 Binary Counters 6405 – 6405 – 5 ...

Page 7

... Physical Dimensions inches (millimeters) 16-Lead Ceramic Dual-In-Line Package (J) Order Number DM54LS190J DM54LS191J 16-Lead Small Outline Molded Package (M) Order Number DM74LS190M DM74LS191M NS Package Number J16A NS Package Number M16A 7 ...

Page 8

... Physical Dimensions inches (millimeters) (Continued) 16-Lead Molded Dual-In-Line Package (N) Order Number DM74LS190N DM74LS191N 16-Lead Ceramic Flat Package (W) Order Number DM54LS190W or DM54LS191W LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL ...

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