Rtl, dtl, ttl and cmos family for nand logic and nor logic. Ttl logic in transistortransistor logic ttl, logic gates and other digital circuits are made using bipolar junction transistors and resistors. In the figures below, first is a snapshot of a logic model for draw the linerespect the line. Transistortransistorlogic topics the most commonly used bipolar logic family is transistortransistor logic.
Dtl was initially made with discrete transistors and resistors before being integrated onto silicon. The first diodetransistor logic family of integrated circuits was introduced by signetics in 1962. The following logic families are the most frequently used. That means all the gates belonging to the bipolar family use the transistorised circuits. 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. That model simply specifies all the activities, all the risk and protective factors and all the behaviors designed to affect the two health goals of draw the linerespect the line. The basic circuit in the dtl logic is the nand gate. Among the technologies discussed here are dl, rtl, dtl, ecl, ttl.
It is called so because the logic gating function e. A variant of dtl called highthreshold logic incorporated zener diodes to create a large offset between logic 1 and logic 0 voltage levels. Which of the following is the fastest logic family a. The term transistortransistor is because both logic function and amplification is done by transis. It is a logic family consisting completely of transistors. 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. Dtl inverter circuit theory the dtl inverter uses a transistor and a collector load resistor as shown in the circuit diagram. Diodetransistor logic dtl diodetransistor logic, or dtl, refers to the technology for designing and fabricating digital circuits wherein logic gates employ both diodes and transistors. Each family has its own advantages and limitations. If input x, y or z is low, the corresponding diode conducts current, through the 4. This document describes the main logic families and their characteristics. Logic families electronics sandeep kumar singh bca iind semester 2. These families vary by speed, power consumption, cost, voltage. Characteristics of digital ics digital logic families tech gurukul by dinesh arya check out my amazon store link f.
Actually, there are many different ttl families, with a range of speed, power consumption, and other characteristics. Commercially it starts with the 74 series like the 7404, 74s86 etc. The pmos and i 2 l logic families were used for relatively short periods, mostly in special purpose custom largescale integration. The bipolar families of logic circuits use the bipolar transistors fabricated on the chip. The diodetransistor logic, also termed as dtl, replaced rtl family because of greater fanout capability and more noise margin. In dtl diode transistor logic, all the logic is implemented using diodes and transistors. Ttl transistortransistor logic families history and. Fanout must be examined for both possible output states. Diodetransistor logic dtl is a class of digital circuits that is the direct ancestor of transistortransistor logic. Each ic family has its own characteristics, limitations and advantages. The ic04 locmos he4000b logic datasheet, cross reference, circuit and application notes in pdf format. It has come to existence so as to overcome the speed limitations of dtl family. Within each family, several subfamilies of logic types are. Dtl was first commercial available ic logic family in 5373 series.
Number of logic gates at the next stages that can be loaded to a given logic gate output is the fanout. Ttl is the largest family of digital ics, but the cmos family is growing rapidly. Technology of digital components, ttl logic families, ttl. Emitter coupled logic ecl or current mode logic cml 6.
Ttl input or output lead is defined to be positive if the. Evaluation of logic families using nor and nand logic gates. Digital logic has evolved over the years and this process has led to the development of a variety of families of digital logic integrated circuits. Rtl was superceded in the 1960s by diodetransistor logic and then transistortransistor logic, dtl and ttl respectively. A basic circuit in the dtl logic family is as shown in the figure below. The transistortransistorlogic ttl family was developed in the use of transistor switches for logical operations and defines the binary values as. They deliver speed and drive on a par with ttl, quashing worries about highspeed systems built.
The above two figures show the actual circuit diagram of a circuit where the output of a single nand gate which belongs to a standard ttl transistor transistor logic logic family feeds the inputs of various nand gate which belongs to the same logic family the first figure is for the state when the logic is high and the second figure is during the logic low state. Comparison of mm74hc to 74ls, 74s and 74als logic the mm54hcmm74hc family of high speed logic components provides a combination of speed and power characteristics that is not duplicated by bipolar logic families or any other cmos family, pdf file. The circuit examples in this section are based on a representative ttl family, lowpower schottky ls or lsttl. Pdf diode transistor logic diode logic suffers from voltage degradation from one stage to the next. It suffers from low speed, especially in comparison to ttl. Hundreds of different, but directly interconnectable logic ics are available. Diodetransistor logic dtl essentially diode logic with transistor amplification. A faster logic family called fast schottky f was also introduced that was faster than normal schottky ttl. In the bipolar category there are three basic families called, diode transistor logic dtl, transistor transistor logic ttl and emitter coupled logic ecl. Chapter 5 diode transistor logic university of babylon. One early form of dtl, used by ibm corp in the 360 family of computers, was. Logic families logic families are sets of chips that may implement different logical functions, but use the same type of transistors and voltage levels for logical levels and for the power supplies. Low power schottky lsttl was the industry standard logic family for many years. Early transistorized computers were implemented using discrete transistors, resistors, diodes and capacitors.
It was build in 1961 by james l bui and commercially used in logic design in 1963. Digital logic gates nand and nor are called universal logic gate because. Ttl stands for transistor transistor logic, cmos stands for complementary metal oxide semiconductor and ecl stands for emitter coupled logic. Fill in the banks of the statements below concerning the following logic families. Transistortransistorlogic topics digital design principles ttl.
Transistor logic and then transistortransistor logic, dtl and ttl. One example is the philips norbit family of logic building blocks. The input is connected through a pair of diodes in series with the base of the transistor. Dtl offers better noise margins and greater fanouts than rtl, but suffers from low speed, especially in comparison to ttl. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. A logic probe is a very useful tool for working with digital logic circuits.
The most widely used bipolar technology for digital ics is a. There have been many improvements in logical families such as ttl and cmos. Ttl transistortransistor logic ecl emittercoupled logic mos metaloxide semiconductor cmos complementary metaloxide semiconductor. Because of this diodetransistor logic dtl rapidly replaced rtl in most digital applications. Recommended software programs are sorted by os platform windows, macos, linux, ios, android etc. The he4000b logic family specification datasheet, cross reference. Logic families can be classified broadly according to the. Click on the tab below to simply browse between the. Dtl takes diode logic gates and adds a transistor to the output, in order to provide logic inversion and to restore the signal to full logic levels.
The families rtl, dtl, and ecl were derived from the logic circuits used in early computers, originally implemented using discrete components. Hef schmitttrigger in the he4000b logic family specification family specifications hef, hec he4000b hef40240b hef40240bd hef40240bt. Logic family 3 schottky ls, internal resistance values were increased to reduce power consumption and increase switching speed over the original version. The diode connected directly to the transistor base serves to raise the input. The introduction of advanced lowpower schottky als further increased speed and reduced power consumption. Diode logic pdf complete license key only permits the or and. Dr l is a basic logic family and, as a group of circuits, plays little part in logic. The ic04 locmos he4000b logic family specifications hef, hec pdf 2 download hef package outlinesinfo. A family of simple resistortransistor logic integrated circuits was developed at fairchild semiconductor for the apollo guidance computer in the diodetransistor logic, also termed as dtl, replaced rtl family because of greater fanout capability and more noise margin. Diode logic is used extensively but not in integrated circuits. The electronic components used in the construction of the basic circuit are usually used as. Which of the following logic has the fan out of more than 50 a. Each logic family has its own basic electronic circuit upon which more complex digital circuits and functions are developed. The popularity of these ttl families stem from their ease of use, low cost, mediumtohigh speed operation, and good output drive capability.
Logic families significance and types of logic families. Although nowadays they have been replaced in many applications by bigger, faster smarter chips, the 74 series families continue to play an important role in electronics, and learning about them is a sound basis for. Zion fanout the fanout of a logic gate is the number of inputs that the gate can drive without exceeding its worstcase loading specifications. Many logic families were produced as individual components, each containing one or a few related basic logical functions, which could be used as buildingblocks to create systems or as socalled glue to. Here is a schematic diagram for a logic probe built using comparators. 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. A logic family is a collection of different integratedcircuit chips that have similar input, output, and internal circuit characteristics, but they perform different logic functions and, or, not, etc. It indicates high and low logic states by means of leds, giving visual indication only if the voltage levels are appropriate for each state. Diodetransistor logic dtl was used in the ibm 608 which was the first alltransistorized computer.
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