Ttl and cmos logic families pdf

The two basic logic families are cmos complementary metal oxide. Cmos logic families many families of logic exist beyond static cmos comparison of logic families for a 2input multiplexer briefly overview pseudonmos differential cvsl dynamicdomino complementary passgate. Ttl and cmos characteristics purpose logic gates are classified not only by their logical functions, but also by their logical families. Introduction a logic family of monolithic digital integrated circuit devices is a group of electronic logic gates constructed using one of several different designs, usually with compatible logic levels and power supply characteristics within a family a logic family may also refer to a set of techniques. Logic family 4 the cmosttl logic level problem interconnecting any two logic families often required special techniques such as additional pullup resistors, or purposebuilt interface circuits, since the logic families may use different voltage levels to represent 1 and 0 states. Digital logic families phys3360aep3630 lecture 26 these also have lower power requirements than the standard ttl these also have lower power requirements than the standard ttl these also have lower power requirements than the standard ttl these also have lower power requirements than the standard ttl overview integration, moores law early families dl, rtl t. Digital logic families in hindi tech gurukul by dinesh arya duration. When 5v supply is given to ttl and cmos ics, logic levels of ttl and cmos are different. Presentday building block logic gate ics are based on the ecl, ttl, cmos, and bicmos families. Today the most widely used is something called cmos.

Of these families, only ecl, ttl, nmos, cmos, and bicmos are currently. Emitter coupled logic ecl or current mode logic cml 6. Cmos complementary metal oxide semiconductor is also another classification of ics that uses field effect transistors in the design. Logic families can be classified broadly according to the. Perhaps the most important factor in the use of such gates is the presence of. As, f, ls, s, ttl logic guide introduction and contents todays applications are evolving with greater functionality and smaller size. The threshold level, logic level or transition point is shown to the left of the voltage range.

The graph provides a comparison of input and output io logic switching levels for the cmos, ttl, mixed cmos ttl, etl, btl, gtl, and low voltage glue logic families. Cmos and ttl are the two most widely used logic families. There are various logic families namely diode logic dl resistortransistor logic rtl diodetransistor logic dtl emitter coupled logic ecl logic families can be classified broadly according to the technologies they are built with transistortransistor logic ttl cmos logic ttl and cmos logic family is most widely used ic. Interconnecting any two logic families often required special techniques such as additional pullup resistors, or purposebuilt interface circuits, since the logic families may use different voltage levels to represent 1 and 0 states, and may have other interface requirements only met within the logic family. In fact logic gates can be implemented in pneumatic and hydraulic systems for special purpose applications in hazardous areas in petrochemical plants. For example, a certain amount of current is needed in order to operate correctly. The circuit examples in this section are based on a representative ttl family, lowpower schottky ls or ls ttl. The name is derived from the use of two bipolar junction transistors or bjts in the design of each logic gate. Ttl families use basically the same logic levels as the ttl compatible cmos families in section 3. Transistortransistor logic ttl is a class of digital circuits built from bipolar junction transistors bjt and resistors. Dec 29, 2019 logic families are defined as a group of electronic logic gates and circuits used in ic integrated circuits. Some of the main ttl and cmos subfamilies currently in use are compared in fig. Ttl differences from cmos asymmetric input and output characteristics.

Each ic family has its own characteristics, limitations and advantages. It was build in 1961 by james l bui and commercially used in logic design in 1963. New technologies are continually being developed in an effort to improve the logic. Ttl logic switching levels and a comparison of the different logic families. Its name signifies that transistors perform both the logic function the first transistor and the amplifying function the second transistor. This document describes the main logic families and their characteristics. Characteristics of logic families are speed, fanin, fanout, noise immunity, power dissipation. Difference between cmos and ttl difference between. The types of logic devices are classified in families, of which the most important are ttl and cmos. Ttl transistortransistor logic families history and. Logic families electronics sandeep kumar singh bca iind semester 2. Transistors are basically fancyspeak for electrically controlled switches. There have been many improvements in logical families such as ttl and cmos.

How can we compare and contrast ttl and cmos logic families. Although ics belonging to the same logic family have no special interface requirements, that is, the output of one can directly feed the input of the other, the same is not true if we have to interconnect digital ics belonging to different logic families. The popularity of these ttl families stem from their ease of use, low cost, mediumtohigh speed operation, and good output drive capability. Ttl is the largest family of digital ics, but the cmos family is growing rapidly. Interfacing logic familiesinterfacing logic families when using ttl logic to drive cmos logic the high level voltage of the ttl output must be increased with a pullup resistor. Als, as, f, ls, s, ttl logic guide introduction and contents todays applications are evolving with greater functionality and smaller size.

Integration levels gatetransistor ratio is roughly 110. Chapter 2 digital circuits ttl and cmos based on chapter 3. It is a logic family consisting completely of transistors. Which logic family has the highest power dissipation per gate a. All logic families have key specifications that their parts abide to. It is called transistortransistor logic because both the logic gating function and the amplifying function are performed by transistors. Four major logic families that predominated from the 1970s through the 1990s are transistortransistor logic ttl, complementary metaloxidesemiconductor logic cmos, pronounced seamoss, low voltage ttl logic lvttl, and low voltage cmos logic lvcmos. It relies on circuits built from bipolar transistors to achieve switching and maintain logic states. Each logic family provides chips with a variety of logic functions such as logic gates, buffers, flipflops, and counters. Ttl transistortransistor logic, made of bipolar transistors. Cmos complimentary mos cmos considerably lower energy consumption than ttl and ecl, which. Standard ttl 74 xxxll, low power ttl 74lxx low power schottky. Actually, there are many different ttl families, with a range of speed, power consumption, and other characteristics. Cmos circuits do not draw as much power as ttl circuits while at rest.

Normal active drive logic both high and low states. Nov 20, 2017 prebook pen drive and g drive at teacademy. Cmosttl power requirements ttl power essentially constant no frequency dependence cmos power scales as f c v2 at high frequencies mhz cmos dissipates more power than ttl overall advantage is still for cmos even for very fast chips only a relatively small portion of complicated circuitry operates at highest frequencies frequency. Ecl emitter coupled logic for extremely high speeds. The output stage of most ttl logic is a totempole circuit. Circuit topology output stages three different types. Ttl input or output lead is defined to be positive if the. Due to longer rise and fall times, the transmission of digital signals becomes.

In computer engineering, a logic family may refer to one of two related concepts. For this course, we need to study only ttl and cmos mostly ttl. I will just quote a part from difference between cmos and ttl. Low power schottky lsttl was the industry standard logic family for many years. This page compares ttl vs cmos vs ecl logic families and mentions difference between ttl and cmos and ecl based on various parameters such as fanout,power consumption,noise immunity etc.

Zion fanout the fanout of a logic gate is the number of inputs that the gate can drive without exceeding its worstcase loading specifications. Characteristics of ttl families table 311, page 167. There are various logic families namely diode logic dl resistortransistor logic rtl diodetransistor logic dtl emitter coupled logic ecl logic families can be classified broadly according to the technologies they are built with transistortransistor logic ttl cmos logic ttl and cmos logic family is most widely used ic technologies. Logic family 2 circuits applications such as cpus and memory chips which fall outside of the scope of this article. Ttl circuits consumes more power compared to cmos circuits at rest. The set of logic gates constructed using coupled transistors and resistors are collectively known as ttl gate family. Ttl stands for transistor transistor logic, cmos stands for complementary metal oxide semiconductor and ecl stands for emitter coupled logic. To overcome the shortcomings of ttl gates more technologically advanced methodologies were designed for gates construction, such as pmos, nmos and the most recent and popular complementary metal oxide semiconductor type, or cmos. Little logic guide table of contents introduction as the world leader in logic, texas instruments ti offers a full spectrum of logic functions and technologies including bicmos, bipolar, and the latest advanced cmos families. The transistortransistorlogic ttl family was developed in the use of transistor switches for logical operations and defines the binary values as. However, cmos power consumption increases faster with higher clock speeds than ttl does.

Cmos complementary metal oxide semiconductor made from mosfets. Characteristics of logic families in digital electronics. Logic families are sets of chips that may implement different logical functions, but use. Fill in the banks of the statements below concerning the following logic families.

There are many logic families, but most are variations of ttl, cmos, or lvds. Concept of ttl logic family with questions digital. To give concreteness to our study of ecl, in the following we shall consider the popular ecl 10k in some detail. This page covers ttl to cmos ic interfacing and cmos to ttl ic interfacing. Pdf on apr 20, 2017, shree krishna khadka and others published comparison of ic logic families find. Ti offers process technologies with the logic performance and features needed.

Bipolar transistor transistor logic ttl first introduced by in 1964 texas instruments ttl has shaped digital technology in many ways standard ttl family e. Lower current draw requires less power supply distribution, therefore causing a simpler and cheaper design. Transistortransistor logic first introduced by in 1964 texas instruments ttl has shaped digital technology in many ways one of the most widely used families for small and mediumscale devices rarely used for vlsi standard ttl family e. The basic classification of the logic families are as follows. Ttl logic families free download as powerpoint presentation.

The logic family refers to the general physical realization of a logical element, such as the ttl, emittercoupled logic ecl, or complementary metaloxide semiconductor cmos logic families. It also mentions how to interface led and lamps with ttl or cmos ic. Within each logic family are one or more logic series that have distinctive characteristics, relative to other series within the same logic family. The graph provides a comparison of input and output io logic switching levels for the cmos, ttl, mixed cmosttl, etl, btl, gtl, and low voltage glue logic families. What are the basic differences between cmos and ttl signals. Each family has its own advantages and limitations. In any implementation of a digital system, an understanding of a logic elements physical capabilities and limitations, determined by its logic family, are critical to proper operation. You may wonder why the nand gate is so popular in the ttl logic families.

When cmos logic is expected to drive ttl logic, the cmos gate may not have the current capability to drive the ttl gate. Ttl circuits utilize bjts bipolar junction transistors while cmos circuits utilize fets field effect transistors. Sep 29, 2012 the set of logic gates constructed using coupled transistors and resistors are collectively known as ttl gate family. The ecl logic gates usually have both an or and a nor output.

A bipolar families b mos families c hybrid devices. Difference between cmos and ttl compare the difference. Difference between ttl cmos ecl ttl vs cmos vs ecl. Ti offers the most advanced logic technology while still maintaining support for traditional logic products. I am just showing that in ttl there are so, many resistances and transistors, bipolar. Logic voltage thresholds for ttl, cmos, lvcmos, and gtlp. If you are looking for answer to specific questions, you can search them here.

The circuit examples in this section are based on a representative ttl family, lowpower schottky ls or lsttl. Cmos can be made compatible with ttl t cmos logic families cmos vs. Figure1 depicts ttl to cmos interfacing and cmos to ttl interfacing circuits. Cmos allows a much higher density of logic functions in a single chip compared to ttl. Cmos allows a much higher density of logic functio. Commercially it starts with the 74 series like the 7404, 74s86 etc.

Logic families are offered at every priceperformance node along with benchmark delivery, reliability. Logic voltage thresholds for ttl, cmos, lvcmos, and gtlp ic. They deliver speed and drive on a par with ttl, quashing worries about highspeed systems built with cmos alone. Cmos chips are a lot more susceptible to static discharge compared to ttl chips. There are cmos chips that have ttl logic and are meant as replacements for ttl chips. They deliver speed and drive on a par with ttl, quashing worries about highspeed systems built with cmos. All of these technologies were developed in the 1950s1960s and evolved over. Logic families and their characteristics website staff ui. Oct 05, 2017 on this channel you can get education and knowledge for general issues and topics.

Among the technologies discussed here are dl, rtl, dtl, ecl, ttl, cmos and bicmos. Ttl families use basically the same logic levels as the ttlcompatible cmos families in section 3. Logic families are defined as a group of electronic logic gates and circuits used in ic integrated circuits. Cmos vs ttl ttl stands for transistortransistor logic.

There are different families of logic gates in digital logic design. Fanout must be examined for both possible output states. Overview integration, moores law early families dl, rtl ttl evolution of ttl family ecl cmos family and its evolution overview 2. Transistortransistor logic ttl is a logic family built from bipolar junction transistors. Types of logic families in digital electronics are ttl, cmos complementary metaloxide semiconductor, ecl, rtl, dtl.