Example 7486 74h86 74l86 74s86 74ls86 74as86 74als86 various series of the cmos logic family. The most commonly used bipolar logic family is transistortransistor logic. A philosophy for implementation of threevalue logic is introduced utilizing the tristate concept found in conventional t 2 l buffers. This document describes the main logic families and their characteristics. Ecl emitter coupled logic suitable for systems requiring highspeed operations mos metal oxide semiconductor logic. The circuit examples in this section are based on a representative ttl family, lowpower schottky ls or ls ttl. Ttl series standard ttl highspeed ttl lowpower ttl schottky ttl lowpower schottky ttl advanced schottky ttl advanced lowpower schottky ttl. Ttl and cmos characteristics purpose logic gates are classified not only by their logical functions, but also by their logical families.
It is called transistortransistor logic because both the logic gating function and the amplifying function are performed by transistors. Ic gates are classified not only by their logic operation, but also the specific logic circuit family to which they belong. 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 transistortransistor logic families history and. Low power schottky lsttl was the industry standard logic family for many years. The introduction of advanced lowpower schottky als further increased speed and reduced power consumption. Zion fanout the fanout of a logic gate is the number of inputs that the gate can drive without exceeding its worstcase loading specifications. The ttl family the input of a ttl logic gate is characterized by a multi emitter transistor. Integrated circuits integrated circuits ics are chips, pieces of semiconductor material, that contain all of the transistors, resistors, and capacitors necessary to. Dtl uses diodes and transistors, ttl uses transistors as the main elements. The original name for ttl was transistorcoupled transistor logic tctl. Strada 7 palazzo r3, highspeed, highdrive logic for 3. Logic family 3 schottky ls, internal resistance values were increased to reduce power consumption and increase switching speed over the original version.
A faster logic family called fast schottky f was also introduced that was faster than normal schottky ttl. They deliver speed and drive on a par with ttl, quashing worries about highspeed. Bipolar transistor transistor logic ttl first introduced by in 1964 texas instruments ttl has shaped digital technology in many ways standard ttl family e. Ttl logic family free download as powerpoint presentation. Fanout must be examined for both possible output states. Within each family, several subfamilies of logic types are available, with different rating for speed, power consumption, temperature range. Among the technologies discussed here are dl, rtl, dtl, ecl, ttl. Ttl input or output lead is defined to be positive if the. Buie of trw, which declared it, particularly suited to the newly developing integrated circuit design technology. There have been many improvements in logical families such as ttl and cmos.
Digital logic gate tutorial basic logic gates electronicstutorials. Ttl logic in transistortransistor logic ttl, logic gates and other digital circuits are made using bipolar junction transistors and resistors. In fact, ti is the only logic manufacturer with a 3. The popularity of these ttl families stem from their ease of use, low cost, mediumtohigh speed operation, and good output drive capability. The term transistortransistor is because both logic function and amplification is done by transis. Transistortransistor logic topics the most commonly used bipolar logic family is transistortransistor logic. Generally, a ttl output does not rise high enough to be reliably recognized as a logic 1 by a cmos input, especially if it is only connected to a highinputimpedance cmos input that does not source significant current.
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. Simple gates, counters, buffers, multiplexers, decoders, latches and other interesting functions. Each logic family has its own basic electronic circuit upon which more complex digital circuits and functions are developed. 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. This notation of ttl or cmos refers to the logic technology used to manufacture the integrated circuit, ic or a chip as it is more commonly called.
Ttl has become the most popular family in ssi small scale integration and msi medium scale integration chips, while ecl is the fastest logic family which is used for high speed applications. The following logic families are the most frequently used. Logic families and their characteristics ee280 lecture 8 9 2 ttl transistortransistor logic standard logic family. 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. The output stage of most ttl logic is a totempole circuit. Each ic family has its own characteristics, limitations and advantages. In computer engineering, a logic family may refer to one of two related concepts. From the collection, a scannedin computerrelated document. In ttl transistortransistor logic, think that the device using this technology is made from several transistors.
This now offers the opportunity of using mixed cmos and ttl families at various power. Ti warrants performance of its hardware products to the specifications applicable at the time of sale in. 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. It was build in 1961 by james l bui and commercially used in logic design in 1963. The ttl family is very fast and reliable, and newer faster, less powerconsuming, etc. Digital logic gates nand and nor are called universal logic gate because we can. The most commonly available logic ics are the 74 series family and its subfamilies, identifiable. The first commercial integratedcircuit ttl devices were manufactured by sylvania in 1963, called the sylvania universal highlevel logic family suhl. Wh l i ttl nand i l h when at least one input to a ttl nand gate is low, the.
A free file archiver for extremely high compression keepass. With so many options available, it can be hard to know which family s, ttl logic family. Lately, there has been much interest in lvc, the 5v tolerant logic device family designed for medium performance needs speed 6. Ttl logic gates are rapidswitching devices the sn7400, for example, takes just 15 ns to change state. Many logic families were produced as individual components, each. In this article, you will find the study notes on logic families which will cover the topics such as integrated circuits, characteristics of digital circuits, logical families, digital ic terminology, dl, rtl, dtl and ttl. By utilizing the high impedance state as a distinct logic input as well as output, a threevalued logic family can be constructed. Ttl logic family logic gate integrated circuit scribd.
It is a logic family consisting completely of transistors. This product contains digital input and output devices that use ttl compatible logic levels. Fill in the banks of the statements below concerning the following logic families. Transistor transistor logic ttl and emitter coupled logic ecl. Ttl evolution schottky series 74ls00 ttl a major slowdown factor in bjts is due to transistors going inout of saturation shottky diode has a lower forward bias 0. 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. Multiemitter input transistor is a striking feature of ttl logic family. 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. Logic levels describe which voltage values are interpreted as being on or off.
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