Digital logic is the basis of electronic systems, such as computers and cell phones. Based on an analysis of a typical ttl logic gate circuit consult a datasheet for a ttl logic gate if you need an internal schematic diagram for a gate circuit, determine what logic state is assumed by a ttl gate input when left. Not, or, and and gates are the basic types of gates. The logic not gate is the most basic of all the logical gates and is often referred to as an inverting buffer or simply an inverter. Realize the ex or gates using minimum number of nand gates. For practice or experiment using logic gate you can use logic gate made of switch, diode, relay and so on. Function of a logic gate is expressed using truth table.
Boolean functions are implemented using logic gates. Ttl logic gates are rapidswitching devices the sn7400, for example, takes just 15 ns to change state. We will see the different logic levels in ttl circuits, cmos circuits, some simple logic gates like or, not, nand, and, etc. Ttl logic gates are available at mouser electronics. It is an electronic circuit having one or more than one input and only one output. To acquaint yourself with the properties of and, nand, nor, and exclusiveor gates, the application of boolean algebra to digital. Transistortransistor logic ttl is a digital logic design in which bipolar transistor s act on directcurrent pulses.
Anne bracy cs 3410 computer science cornell university the slides are the product of many rounds of teaching cs 3410 by professors weatherspoon, bala, bracy, and sirer. Concept of ttl logic family with questions digital. Transistors are basically fancyspeak for electrically controlled switches. A logic gate has the basic format shown below in figure 41. It has a propagation delay of 6 ns but average power. Onsemi, alldatasheet, datasheet, datasheet search site for electronic components and semiconductors, integrated circuits, diodes, triacs, and other semiconductors. Many ttl logic gate s are typically fabricated onto a single integrated circuit ic. Not, nor, nand logic functions are usually expressed with and, or, and not properties of logic gates completeness can implement any truth table with and, or, not demorgans law. In this tutorial, we will have a brief introduction to logic gates. Bright india public school affiliated to cbse curriculum investigatory project on logic gates guided by. The interconnection of gates to perform a variety of logical operation is called logic. A voltage transfer curve is a graph of the input voltage to a gate versus its output voltage. This system facilitates the design of electronic circuits that convey information, including logic gates. The interconnection of gates to perform a variety of logical operation is called logic design.
Abt, ahct, hct, act, bipolar, lv1t, lv4t is voh higher than vih. Based on this, logic gates are named as and gate, or gate, not gate etc. Logic operation is same as the open collector output. The minimum input voltage guaranteed to be recognised as logic 1. Digital logic gate functions include and, or and not. The following is a list of 7400series digital logic integrated circuits. Generally speaking, ttl logic ics use npn and pnp type bipolar junction transistors while cmos logic ics use complementary mosfet or jfet type field effect transistors for both their input and output circuitry.
Both q2 and q3 are modeled as saturated, an assumption that must be verified. Physics investigatory project class 12 on topic logic gates. Ttl nor and or gates logic gates electronics textbook. Digital logic or gate digital gates electrical technology. As well as ttl and cmos technology, simple digital logic gates can also be made by connecting together diodes, transistors and resistors to produce rtl, resistortransistor logic. The digital ics are designed using any of either bipolar devices or mos or a combination of both. Give the truth table for exnor and realize using nand gates. Almost any small signal diodes and npn transistors can be used.
A logic gate is a building block of a digital circuit. Low power schottky lsttl was the industry standard logic family for many years. Logic and gate tutorial with logic and gate truth table. Basic logic gates and, or, and not gates objectives. Basic logic gates and gate the and gate is an electronic circuit that gives a high output 1 only if all its inputs are high. Ttl nand and and gates logic gates electronics textbook. Lowvoltage logic lvc designers guide texas instruments. Which logic family has the highest power dissipation per gate a. The logic families which fall under the first kind are called bipolar families, this include diode logic dl, emitted coupled logic ecl, resistor transistor logic rtl, diode transistor logic dtl, transistor transistor logic ttl. This is the basis for the operation for your computer and any. Ttl transistortransistor logic families history and. The original 7400series integrated circuits were made by texas instruments with the prefix sn to create the name sn74xx. A ttl nand gate can be made by taking a ttl inverter circuit and adding another input.
It takes one or more binary signals as its inputs, and using a specific algorithm, outputs a single bit. Texas instrumentslogic guide 20174 logic guide 2017texas instruments 4 logic overview ic basics. Lab 1 part 2 identify the 7400 series ttl gates and look up their data sheets. Electrical characteristics of gates in the ideal digital world we have considered up to now, all low logic signals have been considered to be 0v ground and all high logic signals have been considered to be at the power supply voltage vcc. In order to turn this nor gate circuit into an or gate, we would have to invert the output logic level with another transistor stage, just like we did with the nandtoand gate example. A gate is an electronic device which is used to compute a function on a two valued signal. It relies on circuits built from bipolar transistors to achieve switching and maintain logic states.
What are the logic low and high levels of ttl ics and cmos ics. Advantages of ttl logic family, one should have a basic idea about rtl, dtl etc. Logic not gate tutorial with logic not gate truth table. Logic gates not, or, and, nor, nand, xor, xnor gate, pdf. Cmos technology and logic gates mit opencourseware. Logic gates pdf download logic gates pdf ict logic gates logic gates definition of logic gates pdf electronics logic gates logic gates mcq questions and answers logic gates and boolean algebra 1 thing kevin gates download praying through the gates of time download tom gates epic adventure pdf free download applying logic in chess pdf free download download. Basic logic gates and, or, and not gates objectives find, read and cite all the research you need on researchgate. Low level state when lower transistor is on and upper transistor is off. Describe and, or or nand, nor logic gates realize logic gates belonging to different logic families such as dtl, ttl and cmos understand the factors that define the performance of a logic gate. A pmos transistor acts as an inverse switch that is on when the controlling signal is low and off when the controlling signal is high. Bipolar transistor transistor logic ttl first introduced by in 1964 texas instruments ttl has shaped digital technology in many ways standard ttl family e. In this electronics 201 lecture, we look at how to construct any logic gate imaginable from simple npn transistors using not logic. And this is standard diagram of the internals of a single nand gate inside such a package.
Fill in the banks of the statements below concerning the following logic families. Pdf on jun 9, 2018, mohammed qasim taha and others published lab 1. This is what a ttl quad ie contains 4 nand gate package looks like. The ttl family is based on the bipolar junction transistor, and was the first commonly available series of logic elements. Digital electronics relies on the actions of just seven types of logic gates, called and.
Transistor transistor logic gate electronics tutorials. An nmos switch is on when the controlling signal is high and is off when the controlling signal is low. Use of transistors q4 and diode is to provide quick charging and discharging of parasitic capacitance across q3. Ttl nand gates can be designed with any desired number of inputs simply by changing the number of diodes in the diode and gate in the figure. This time the admin will explain the types of logic gate ic along with the schematics that can be used for practice. Ttl has several subfamilies having different speed and power dissipation characteristics as detailed below. Nttl total number of outputs where corresponding input is at the ttl level. Logic and gates are available using digital circuits to produce the desired logical function and is given a symbol whose shape represents the logical operation of. Most logic gates have two inputs and one output and are based on boolean algebra. At any given moment, every terminal is in one of the two binary conditions false high or true low. Logic gates are the basic building blocks of any digital system.
Resistor is used to keep the output current to a safe value. The circuit model for the ttl gate with all inputs high is shown in figure 5. What is logic gate and, or, xor, not, nand, nor and xnor. Introduction to logic gates not, and, nand, or, nor. Due to the popularity of these parts, other manufacturers released pintopin compatible logic devices which kept the 7400 sequence number as an aid to identification of compatible parts. The truth table and equivalent gate circuit an invertedoutput nor gate are shown here. The basic operations are described below with the aid of truth tables. The popularity of these ttl families stem from their ease of use, low cost, mediumtohigh speed operation, and good output drive capability.
Describe in your lab report each of their functions. Published under the terms and conditions of the design science license. A ttl input signal is defined as low when between 0 v and 0. Also show their logic symbol, use the function in an equation and show the truth table for one gate in each of the integrated circuits.
An and gate may be created by adding an inverter stage to the output of the nand gate circuit. Let us investigate some of such circuits using dioderesistor logic drl, diodetransistor logic dtl and transistortransistor logic ttl as described below. Within usefully broad limits, logic gates could be treated as ideal boolean devices without concern for electrical limitations. If a certain condition is true, it turns on and goes off when the condition is false. The minimum output voltage in high state logic 1 2.
Logic gates practice problems key points and summary first set of problems from q. The gate does indeed perform the nand function, with the truth table and logic symbol shown in b and c. Digital logic is rooted in binary code, a series of zeroes and ones each having an opposite value. Logic gates types, working principle, application, advantage. Simple basic digital logic gates simple digital logic gates can be made by combining transistors, diodes and resistors as discrete components. The relationship between the input and the output is based on a certain logic. Comparison of switching standards 5v ttl standard ttl.