TERM PAPER

On

“ CMOS IC Counters”

SUBMITTED TO :-

MR.MUKESH THAKUR

DEPT. OF SEEE. SUBIMITTED BY:-

Rahul sharma

SUB. CODE-ECE 202.roll no.-B56

SEC.-E3009 .regd.-11007153

CONTENTS:-1.ACKNOWLEDGEMENT

2.INTRODUCTION.

3.WORKING OF CMOS AND COUNTERS.

.ASYNCHRONOUS COUNTERS.

.SYNCHRONOUS COUNTERS.

.RING COUNTERS.

.MECHANICAL COUNTERS

.COMPUTER SCIENCE COUNTERS.

4.THE 4000 SERIES

.DESIGN CONSIDERATIONS AND ITS TYPES

5.THE 7400 SERIES

.OVERVIEW

6.CONCLUSION

7.REFERENCES

ACKNOWLEDGMENT

I am RAHUL SHARMA student of B.TECH –MBA 2ND YR. 3RD semester Lovely Professional University Phagwara feel highly indebted to the persons who co-operated with me during my project work.

The various persons to whom I am thankful for their expert guidance for completion of my project .I am really thankful to OUR CLASS TEACHER MR.MUKESH THAKUR for his expert guidance.

I cannot express my feelings in words for love, affection and insipiration and blessings rendered by my parents.

Above all I am highly indebted to “GOD” without whose grace this little work could have never seen light of the day.

Introduction:-

Digital (or logic) circuits can only have one of two states; logical 1 or 'high' and logical 0 or 'low'. In adigital circuit these are represented by two voltages, 'high' being close to the positive supply rail and 'low'being close to the negative supply rail (or ground). This should be contrasted to analogue circuits such asamplifiers where any voltage between these values is valid. The simplicity of logic circuits, having onlytwo states, allows them to be used in a wide variety of applications such as, computing circuits, logicfunctions and counter circuits. The CMOS 4000 series provides a wide range of integrated circuitscovering a variety of useful digital functions and have the advantages of a wide power supply range (3 to15 Vdc) and low power consumption.Fortunately the IC's themselves are inexpensive and with a solderless breadboard, some LED's, resistorsand switches you can be well on your way to building your own circuits using these versatile components!This page shows the pin-outs and the functionality of each IC and what the various inputs and outputs do.Before describing each IC, first a note about input and output connections and handling precautions.

Interfacing to CMOS logic IC'sA logic input pin can be set to a logical 'low' by connecting it to the ground (Gnd) rail (usually batterynegative), similarly a logic 'high' is set by connecting it to Vcc (or the positive battery terminal). An inputshould not be allowed to 'float' between these two states as this can cause unpredicable operation.All the CMOS IC's require two of their pins to be always connected to a power supply for properoperation (Vcc = +, Gnd = -), logic diagrams often omit these connections!CMOS output pins can drive an LED connected to Gnd via a suitable resistor (680 ohms is OK for 9 voltoperation). A lit LED then indicates a 'high' output whereas an unlit LED indicates a 'low' output state.That LED could also be a segment of a 7 segment display and some of the CMOS counters providesoutputs that do just that, each segment will require its own resistor. External transistors should be used todrive higher current loads (e.g. filament lamps).The counter IC's require a 'clock', this is just a series of positive and negative pulses (a square-wavesignal) and can be provided by a switch (although most switches suffer from contact 'bounce' and givemultiple pulses with one press!) or an 'oscillator' circuit (e.g. the 4047 IC) which provides a constant clockfrequency. The CMOS counter IC's advance (increment) on negative to positive clock transitions thus thecounting rate is the same as that of the clock frequency.

Handling precautions

Anti-static precautions should be taken when handling and storing CMOS IC's, store unused IC's inanti-static conductive foam, ground yourself (i.e. to a radiator pipe) before handling the IC's, finally, whensoldering always use a socket and do not solder to the pins directly. Usually more elaborate precautionssuch as anti-static mats, wrist straps etc are not required unless your local humidity is exceptionally dry.

CMOS IC's by number/function

The pin out diagrams provided assume that the IC is the usual way round with the notch at the top and thepins sticking downwards (i.e. as they would be inserted into a PCB or breadboard). No circuit diagramshave been provided however the function of each IC pin is described so that you can connectswitches/LED's to the various input/outputs and try out the different functions in your own circuits. I havealso suggested possible applications for each IC, but complete systems can easily be built byinterconnecting the various functions

INTRODUCTION OF CMOS -

Complementary metal–oxide–semiconductor (CMOS) is a technology for

constructing integrated circuits CMOS technology is used in

microprocessors, microcontrollers, static RAM, and other digital logic circuits. CMOS

technology is also used for several analog circuits such as image sensors (CMOS sensor), data

converters, and highly integrated transceivers for many types of communication. Frank

Wanlass patented CMOS in 1967 (US patent 3,356,858).

CMOS is also sometimes referred to as complementary-symmetry metal–oxide–

semiconductor (or COS-MOS). The words "complementary-symmetry" refer to the fact that the

typical digital design style with CMOS uses complementary and symmetrical pairs of p-

type and n-type metal oxide semiconductor field effect transistors (MOSFETs) for logic

functions.

Two important characteristics of CMOS devices are high noise immunity and low static power

consumption. Significant power is only drawn when the transistors in the CMOS device are

switching between on and off states. Consequently, CMOS devices do not produce as

much waste heat as other forms of logic, for example transistor-transistor logic (TTL) or NMOS

logic. CMOS also allows a high density of logic functions on a chip. It was primarily for this

reason that CMOS became the most used technology to be implemented in VLSI chips.

The phrase "metal–oxide–semiconductor" is a reference to the physical structure of certain field-

effect transistors, having a metal gate electrode placed on top of an oxide insulator, which in turn

is on top of a semiconductor material. Aluminum was once used but now the material is poly

silicon. Other metal gates have made a comeback with the advent of high-k dielectric materials

in the CMOS process, as announced by IBM and Intel for the 45 nanometer node and beyond.

WORKING OF CMOS:-

"CMOS" refers to both a particular style of digital circuitry design, and the family of processes

used to implement that circuitry on integrated circuits (chips). CMOS circuitry dissipates less

power than logic families with resistive loads. Since this advantage has increased and grown

more important, CMOS processes and variants have come to dominate, thus the vast majority of

modern integrated circuit manufacturing is on CMOS processes. As of 2010, CPUs with the

best performance per watt each year have been CMOS static logic since 1976.CMOS circuits use

a combination of p-type and n-type metal–oxide–semiconductor field-effect

transistors (MOSFETs) to implement logic gates and other digital circuits found in computers,

telecommunications equipment, and signal processing equipment. Although CMOS logic can be

implemented with discrete devices (e.g., for instructional purposes in an introductory circuits

class), typical commercial CMOS products are integrated circuits composed of millions of

transistors of both types on a rectangular piece of silicon of between 10 and 400mm2. These

devices are commonly called "chips", although within the industry they are also referred to as a

"die" (singular) or "dice", or "dies" (plural).

Counters:-

In digital logic and computing, a counter is a device which stores (and sometimes displays) the

number of times a particular event or process has occurred, often Electronic counters.

In electronics, counters can be implemented quite easily using register-type circuits such as

the flip-flop, and a wide variety of classifications exist:

Asynchronous (ripple) counter – changing state bits are used as clocks to subsequent state

flip-flops

Synchronous counter – all state bits change under control of a single clock

Decade counter – counts through ten states per stage

Up/down counter – counts both up and down, under command of a control input

Ring counter – formed by a shift register with feedback connection in a ring

Johnson counter – a twisted ring counter

Cascaded counter

Each is useful for different applications. Usually, counter circuits are digital in nature, and count

in natural binary. Many types of counter circuits are available as digital building blocks, for

example a number of chips in the 4000 series implement different counters.

Occasionally there are advantages to using a counting sequence other than the natural binary

sequence—such as the binary coded decimal counter, a linear feedback shift register counter, or

a Gray-code counter.

Counters are useful for digital (ripple) clocks and timers, and in oven timers, VCR clocks, etc.

Asynchronous counter:-

FIG.-Asynchronous counter created from two JK flip-flops

An asynchronous (ripple) counter is a single JK-type flip-flop, with its J (data) input fed from its

own inverted output. This circuit can store one bit, and hence can count from zero to one before

it overflows (starts over from 0). This counter will increment once for every clock cycle and

takes two clock cycles to overflow, so every cycle it will alternate between a transition from 0 to

1 and a transition from 1 to 0. Notice that this creates a new clock with a 50% duty cycle at

exactly half the frequency of the input clock. If this output is then used as the clock signal for a

similarly arranged D flip-flop (remembering to invert the output to the input), you will get

another 1 bit counter that counts half as fast. Putting them together yields a two-bit counter:

Cycle Q1 Q0(Q1:Q0)dec

0 0 0 0

1 0 1 1

2 1 0 2

3 1 1 3

4 0 0 0

one can continue to add additional flip-flops, always inverting the output to its own input, and

using the output from the previous flip-flop as the clock signal. The result is called a ripple

counter, which can count to 2n − 1 where n is the number of bits (flip-flop stages) in the counter.

Ripple counters suffer from unstable outputs as the overflows "ripple" from stage to stage, but

they do find frequent application as dividers for clock signals, where the instantaneous count is

unimportant, but the division ratio overall is (to clarify this, a 1-bit counter is exactly equivalent

to a divide by two circuit; the output frequency is exactly half that of the input when fed with a

regular train of clock pulses).

The use of flip-flop outputs as clocks leads to timing skew between the count data bits, making

this ripple technique incompatible with normal synchronous circuit design styles.

Synchronous counters: -

[t]s

FIG.-A 4-bit synchronous counter using JK flip-flops

A simple way of implementing the logic for each bit of an ascending counter (which is what is

depicted in the image to the right) is for each bit to toggle when all of the less significant bits are

at a logic high state. For example, bit 1 toggles when bit 0 is logic high; bit 2 toggles when both

bit 1 and bit 0 are logic high; bit 3 toggles when bit 2, bit 1 and bit 0 are all high; and so on.

Synchronous counters can also be implemented with hardware finite state machines, which are

more complex but allow for smoother, more stable transitions.

Hardware-based counters are of this type.

Decade counter:-

A decade counter is one that counts in decimal digits, rather than binary. A decade counter may

have each digit binary encoded (that is, it may count in binary-coded decimal, as

the 7490 integrated circuit did) or other binary encodings (such as the bi-quinary encoding of

the 7490 integrated circuit). Alternatively, it may have a "fully decoded" or one-hot output code

in which each output goes high in turn (the 4017 is such a circuit). The latter type of circuit finds

applications in multiplexers and demultiplexers, or wherever a scanning type of behavior is

useful. Similar counters with different numbers of outputs are also common.

The decade counter is also known as a mod-counter when it counts to ten (0, 1, 2, 3, 4, 5, 6, 7, 8,

9). A Mod Counter that counts to 64 stops at 63 because 0 counts as a valid digit.

Up/down counter

A counter that can change state in either direction, under the control of an up/down selector

input, is known as an up/down counter. When the selector is in the up state, the counter

increments its value. When the selector is in the down state, the counter decrements the count.

Ring counter

A ring counter is a Shift Register (a cascade connection of flip-flops) with the output of the last one connected to the input of the first, that is, in a ring. Typically, a pattern consisting of a single bit is circulated so the state repeats every n clock cycles if n flip-flops are used.It can be used as a cycle counter of n states.

Computer science counters

In computability theory, a counter is considered a type of memory. A counter stores a

single natural number (initially zero) and can be arbitrarily many digits long. A counter is usually

considered in conjunction with a finite-state machine (FSM), which can perform the following

operations on the counter:

Check whether the counter is zero

Increment the counter by one.

Decrement the counter by one (if it's already zero, this leaves it unchanged).

The following machines are listed in order of power, with each one being strictly more powerful

than the one below it:

1. Deterministic or non-deterministic FSM plus two counters

2. Non-deterministic FSM plus one stack

3. Non-deterministic FSM plus one counter

4. Deterministic FSM plus one counter

5. Deterministic or non-deterministic FSM

For the first and last, it doesn't matter whether the FSM is a deterministic finite-state machine or

a nondeterministic finite-state machine. They have equivalent power. The first two and the last

one are levels of the Chomsky hierarchy.

The first machine, an FSM plus two counters, is equivalent in power to a Turing machine. See

the article on counter machines for a proof.

Mechanical counters

FIG.MECHANICAL COUNTERS

Mechanical counter wheels showing both sides. The bump on the wheel shown at the top

engages the ratchet on the wheel below every turn.

Long before electronics became common, mechanical devices were used to count events. These typically consist of a series of disks mounted on an axle, with the digits 0 through 9 marked on their edge. The right most disk moves one increment with each event. Each disk except the left-most has a protrusion that, after the completion of one revolution, moves the next disk to the left one increment. Such counters were originally used to control manufacturing processes, but were later used as odometers for bicycles and cars and in fuel dispensers. One of the largest manufacturers was the Veeder-Root company, and their name was often used for this type of counter.

THE 4000 SERIES :-

FIG.-A very early CD4029 counter IC, manufactured by RCA.

The 4000 series is a family of industry standard integrated circuits which implement a variety

of logic functions using Complementary Metal–Oxide–Semiconductor technology, and are still

in use today. They were introduced by RCA as CD4000 COS/MOS series in 1968, as a lower

power and more versatile alternative to the 7400 series of TTL logic chips.[1] Almost all IC

manufacturers active during the era fabricated chips from this series. RCA sometimes advertised

the line as COSMOS, standing for Complementary Symmetry Metal-Oxide Semiconductor. The

naming system followed the RCA convention of CA for analog, CD for digital, but did not relate

to the Texas Instruments SN7400 series numbering scheme.

FIG.-The CD4007 on abreadboard

4000 series parts had the advantage of lower power consumption, wider range of

supply voltages (3 V to 15 V), and simpler circuit design due to the vastly increased fanout.

However their slower speed (initially about 1 MHz operation, compared with bipolar TTL's

10 MHz) limited their applications to static or slow speed designs. Later, new fabrication

technology largely overcame the speed problems, while retaining backward compatibility with

most circuit designs. Although all semiconductors can be damaged by electrostatic discharge, the

high impedance of CMOS inputs makes them more susceptible than bipolar transistor based,

TTL, devices. Eventually, the advantages of CMOS (especially the later series such as 74HC)

edged out the older TTL chips, but at the same time ever increasing LSI techniques edged out the

modular chip approach to design. The 4000 series is still widely available, but perhaps less

important than it was two decades ago.

The series was extended in the late 1970s and 1980s to include new types which implemented

new functions, or were better versions of existing chips in the 4000 series. Most of these newer

chips were given 45xx and 45xxx designations, but are usually still regarded by engineers as part

of the 4000 series.

In the 1990s, some manufacturers (e.g. Texas Instruments) ported the 4000 series to their

newer HCMOS technology with devices such as the 74HCT4060 providing equivalent

functionality to a 4060 IC but with greater speed.

Design considerations

The original 4000 series was available in either unbuffered or buffered inputs and outputs. The

buffered outputs can source or sink more current than the unbuffered outputs, eliminating the

need for discrete switching transistors in some designs. The buffered versions also have faster

output switching times, as the signal rise time of the buffered output stage is faster than that of an

unbuffered device. However the overall propagation delay through the buffered versions is

higher due to the additional circuitry. The buffered devices are more susceptible to

output oscillation with slow-changing inputs. Designers must evaluate the choice of buffered or

unbuffered parts according to the nature of the circuit in which the devices are being used. The

additional input and output gates on the buffered parts also make them marginally less

susceptible to damage by electrostatic discharge (ESD).

Although the original designation for unbuffered and buffered parts was the addition of an 'A' or

'B' suffix to the part code (e.g.: 4000A = unbuffered, 4000B = buffered), some manufacturers

(e.g.: Texas Instruments) later changed to using UB (unbuffered) and B (buffered) suffixes (e.g.:

4000UB and 4000B).

The diagrams below show the construction differences between a simple buffered and

unbuffered CMOS NOR logic gate. Note that the logic gate at the core of the buffered part is

actually a NAND gate, but the overall function of the complete circuit is a NOR gate due to the

logic inversions performed by the buffers. (A negated NAND with negated inputs becomes a

NOR as defined by De Morgan's laws in Boolean Algebra.) The clamping diodes on the inputs

are to offer some protection against ESD.

Fig.-Buffered CMOS two input NOR gate

FIG.-Unbuffered CMOS two input NOR gate

The 4000 series permits the use of "cookbook" design, where standard circuit elements can be

created, shared, and connected to other circuits with few, if any, connection difficulties. This

greatly speeds the design of new hardware by reusing standard approaches to circuit design. In

contrast, TTL circuits, while similarly modular, often require much more careful interfacing,

since the limited fanout (and fan-in) require that the loading of each output be carefully

considered. (Some later TTL families, like 74LS reduce this problem with fanouts of 20.) It is

also much easier to prototype LSIdesigns using the 4000 series and get repeatable and

transferable results when moving to the more integrated design.

Some care needs to be taken with the design of circuits using CMOS chips. Many parts offer

multiple logic gates in a single package and it is common to not need all of them. An engineer

who forgets to 'tie off' (connect the unused gate inputs to VSS or VDD) may find the chip draws

excessive current. The problem is caused by biasing in each gate. With the inputs disconnected,

the gates may be biased into a mode where the outputs are partially conducting; this leaves the

output buffer drawing a great deal of current since it is not fully on or off, creating a low

resistance current path between the power supply rails.

Example common 4000 series chips

4000 - Dual 3-Input NOR Gate and Inverter

4001 - Quad 2-Input NOR Gate

4002 - Dual 4-Input NOR Gate OR Gate

4008 - 4-Bit Full Adder

4010 - hex non-inverting buffer

4011 - Quad 2-Input NAND Gate

4017 - Decade Counter / Johnson Counter

4511 - BCD to 7-segment LED driver

4029 cmos ic counter

Notable parts

A few parts are notable in the 4000 series because of their level of integration compared to other

chips. This list is intentionally incomplete and is meant to provide a sample of the more

interesting parts in the series. Devices useful for switching analog signals (such as the 4066, and

4051 to 4053) have continued to enjoy popularity in some audio designs (although non-4000

series chips, often with less distortion, are now available).

4017 decade counter

The 4017 IC is a 16-pin CMOS decade counter from the 4000 series. It takes clock pulses from

the clock input, and makes one of the ten outputs come on in sequence each time a clock pulse

arrives.

Pinout

Pin number Name Purpose

1 6 The 6th sequential output

2 2 The 2nd sequential output

3 1 The 1st sequential output

4 3 The 3rd sequential output

5 7 The 7th sequential output

6 8 The 8th sequential output

7 4 The 4th sequential output

8 0 V, VDD The connection to the 0 V rail

9 9 The 9th sequential output

10 5 The 5th sequential output

11 10 The 10th sequential output

12 COCarry out output - outputs high on counts 0 to 4, outputs low on counts 5 to 9 (thus a transition from low to high occurs when counting from 9 back to 0)

13 LE Latch enable - latches on the current output when high (i.e. the chip counts when LE is low)

14 CLK Clock in

15 RST Reset - sets output 1 high and outputs 2 through 10 low, when taken high

16 +9 V, VCC The connection to the +VCC rail (voltage between +3 V and +15 V)

Example: Electronic Roulette

Electronic Roulette circuit diagram.

The circuit diagram on the right shows how to create a game of roulette using the 4017 decade

counter and various other electronic parts. The switch stops the roulette, and the resistor adjusts

the spin speed.

4026 counter and display decoder

The 4026 IC is a 16-pin CMOS seven-segment counter from the 4000 series. It counts clock

pulses and returns the output in a form which can be displayed on a seven-segment display. This

avoids using a binary-coded decimal to seven-segment decoder, but it can only be used to display

the (decimal) digits 0-9.

Pinout

Pin number

Name Purpose

1 CLK Clock in

2 CI Clock inhibit - when low, clock pulses increment the seven-segment

3 DEDisplay enable - the chip outputs to the seven-segment when this is high (i.e. when it's low, the seven-segment is off) - useful to conserve battery life, for instance

4 DEO Display enable out - for chaining 4026s

5 COCarry out output - Is high when changing from 9 to 0. It provides an output at 1/10 of the clock frequency, to drive the clock input of another 4026 to provide multi-digit counting.

6 F Output for the seven-segment's F input

7 G Output for the seven-segment's G input

8 VDD The connection to the 0 V rail

9 D Output for the seven-segment's D input

10 A Output for the seven-segment's A input

11 E Output for the seven-segment's E input

12 B Output for the seven-segment's B input

13 C Output for the seven-segment's C input

14 UCSUngated C-segment - an output for the seven-segment's C input which is not affected by the DE input. This output is high unless the count is 2, when it goes low.

15 RST Reset - resets all outputs to low when taken high

16 VSS The connection to the +9 V rail

4511 BCD to seven-segment decoder

The 4511 IC is a 16-pin CMOS BCD to seven-segment decoder from the 4000 series. It takes

the binary-coded decimal from a binary counter and decodes it to drive a seven-segment display.

Pinout

Pin number Name Purpose

1 2s Input for the 2s bit from the binary counter

2 4s Input for the 4s bit from the binary counter

3 LT Lamp test - when low, the chip takes all the segments on the display high (to test connections, etc.)

4 BI Blanking input - when low, the chip does not output to the display - to conserve battery life, for instance

5 LE Latch enable - latches on the current output when high (i.e. the inputs change the output when LE is low)

6 8s Input for the 8s bit from the binary counter

7 1s Input for the 1s bit from the binary counter

8 0 V, VDD The connection to the 0 V rail

9 E Output for the seven-segment's E input

10 D Output for the seven-segment's D input

11 C Output for the seven-segment's C input

12 B Output for the seven-segment's B input

13 A Output for the seven-segment's A input

14 G Output for the seven-segment's G input

15 F Output for the seven-segment's F input

16 +9 V, VCC The connection to the +9 V rail

THE 7400 SERIES:-

The 7400 series of transistor-transistor logic (TTL) integrated circuits are historically important as the first widespread family of TTL integrated circuit logic. It was used to build the mini and mainframe computers of the 1960s and 1970s. Several generations of pin-compatible descendants of the original family have since become de-facto standard electronic components.

Overview

The 7400 series contains hundreds of devices that provide everything from basic logic gates, flip-flops, and counters, to special purpose bus transceivers and Arithmetic Logic Units (ALU). Specific functions are described in a list of 7400 series integrated circuits.

Today, surface-mounted CMOS versions of the 7400 series are used in various applications in electronics and for glue logic in computers and industrial electronics. The original through-hole devices in dual in-line packages (DIP/DIL), which were the mainstay of the industry for many decades, are very useful for rapid breadboard-prototyping and education and so remain available from most manufacturers. The fastest types and very low voltage versions are typically surface-mount only, however.

The 14-pin DIP shown to the right is an example of a 7400 part. The chip contains four two-input NAND gates. Each gate uses two pins for input and one pin for its output, and the remaining two contacts supply power (+5 V) and connects to the ground.

While designed as a family of digital logic, it was not unusual to see TTL chips in analog circuits like Schmitt triggers. Like the 4000 series, the newer CMOS versions of the 7400 series are also usable as analog amplifiers using negative feedback (similar to operational amplifiers with only an inverting input).

The former Soviet Union manufactured the K155ЛA3 which was pin-compatible with the 7400 part available in the United States, except for using a metric spacing of 2.5mm between pins instead of the 1/10"-based (2.54mm) spacing used in the west.

FIG-.Parts of the 7400 series:-

7400 series parts were constructed using bipolar transistors, forming what is referred to as transistor–transistor logic or TTL. Newer series, more or less compatible in function and logic level with the original parts, use CMOS technology or a combination of the two (BiCMOS). Originally the bipolar circuits provided higher speed but consumed more power than the competing 4000 series of CMOS devices. Bipolar devices are also limited to a fixed power supply voltage, typically 5 V, while CMOS parts often support a range of supply voltages.

Milspec-rated devices for use in extended temperature conditions are available as the 5400 series. Texas Instruments also manufactured radiation-hardened devices with the prefix RSN, and the company offered beam-lead bare dies for integration into hybrid circuits with a BL prefix designation. 

Regular speed TTL parts were also available for a time in the 6400 series - these had an extended industrial temperature range of −40 C to +85 C. While companies such as Mullard listed 6400-series compatible parts in 1970 data sheets, by 1973 there was no mention of the 6400 family in the Texas Instruments TTL Data Book. Some companies have also offered industrial extended temperature range variants using the regular 7400 series part numbers with a prefix or suffix to indicate the temperature grade.

As integrated circuits in the 7400 series were made in different technologies, usually compatibility was retained with the original TTL logic levels and power supply voltages. Strictly, an integrated circuit made in CMOS is no longer a TTL chip since it uses field-effect transistors (FETs) and not bipolar junction transistors, but similar part numbers are retained to identify similar logic functions and electrical (power and I/O voltage) compatibility in the different subfamilies. Over 40 different logic subfamilies use this standardized part number scheme.

Bipolar

74 - the "standard TTL" logic family had no letters between the "74" and the

specific part number.

74L - Low power (compared to the original TTL logic family), very slow

H - High speed (still produced but generally superseded by the S-series, used in

1970s era computers)

S - Schottky (obsolete)

LS - Low Power Schottky

AS - Advanced Schottky

ALS - Advanced Low Power Schottky

F - Fast (faster than normal Schottky, similar to AS)

CMOS

C - CMOS 4–15 V operation similar to buffered 4000 (4000B) series

HC - High speed CMOS, similar performance to LS, 12 nS

HCT - High speed, compatible logic levels to bipolar parts

AC - Advanced CMOS, performance generally between S and F

AHC - Advanced High-Speed CMOS, three times as fast as HC

ALVC - Low voltage - 1.65 to 3.3 V, Time Propagation Delay (TPD) 2 NS

AUC - Low voltage - 0.8 to 2.7 V, TPD < 1.9 nS@1.8 VFC - Fast CMOS,

performance similar to F

LCX - CMOS with 3 V supply and 5 V tolerant inputs

LVC - Low voltage – 1.65 to 3.3 V and 5 V tolerant inputs, tpd < 5.5 nS@3.3 V,

tpd < 9 nS@2.5 V

LVQ - Low voltage - 3.3 V

LVX - Low voltage - 3.3 V with 5 V tolerant inputs

VHC - Very High Speed CMOS - 'S' performance in CMOS technology and

power

BiCMOS

BCT - BiCMOS, TTL-compatible input thresholds, used for buffers

ABT - Advanced BiCMOS, TTL-compatible input thresholds, faster than ACT

and BCT

Many parts in the CMOS HC, AC, and FC families are also offered in "T" versions (HCT, ACT, and FCT) which have input thresholds that are compatible with both TTL and 3.3 V CMOS signals. The non-T parts have conventional CMOS input thresholds. The ACTQ family introduced by Fairchild utilizes Quiet Series technology to guarantee quiet output switching and improved dynamic threshold performance. FACT Quiet Series features GTO output control and undershoot corrector in addition to a split ground bus for superior performance. The 74H family is the same basic design as the 7400 family with resistor values reduced. This reduced the typical propagation delay from 9 ns to 6 ns but increased the power consumption. The 74H family provided a number of unique devices for CPU designs in the 1970s. Many designers of military and aerospace equipment used this family over a long period and as they need exact replacements, this family is still produced by Lansdale Semiconductor. The 74S family, using Schottky circuitry, uses more power than the 74, but is faster. The 74LS family of ICs is a lower-power version of the 74S family, with slightly higher speed but lower power dissipation than the original 74 family; it became the most popular variant once it was widely available.

The 74F family was introduced by Fairchild Semiconductor and adopted by other manufacturers; it is faster than the 74, 74LS and 74S families.

Through the late 1980s and 1990s newer versions of this family were introduced to support the lower operating voltages used in newer CPU devices.

Conclusion:-This term paper includes the detail discussion of the cmos ic counters and its various types.

The first part of the term paper includes the introduction of cmos and counters of its various types.and after the detail discussion above we here by came to know that ic counters has very vast usage in future prospects and it is presently the functional part of the many devices which h we are going through daily lives.we all are living in a digital world now and cmos ic counters are the building blocks of these.so, without it we can’t imagine the digital world.

REFERENCES:-

 http://www.play-hookey.com/digital/synchronous_counter.html

Arun kumar singh,  ‘Digital Principles Foundation of Circuit Design and Application’. New

age publishers. (ISBN -8122417590).

 Paul Horowitz and Winfield Hill (1989). ‘The art of Electronics’. Cambridge university press.

( Isbn-0521370957).

 Rudolf f. Graf (1999). ‘Modern Dictionary of Electronics’. Newnes.( Isbn-0750698667).