74ls02 Logic Family
Kerrie Gingrich
In 1964, Texas Instruments introduced the SN5400 series of logic chips, in a ceramic semiconductor package. A low-cost plastic package SN7400 series was introduced in 1966 which quickly gained over 50% of the logic chip market, and eventually becoming de facto standardized electronic components.[4][5] Over the decades, many generations of pin-compatible descendant families evolved to include support for low power CMOS technology, lower supply voltages, and surface mount packages.[6]
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. Some TTL logic parts were made with an extended military-specification temperature range. These parts are prefixed with 54 instead of 74 in the part number. The less-common 64 and 84 prefixes on Texas Instruments parts indicated an industrial temperature range. Since the 1970s, new product families have been released to replace the original 7400 series. More recent TTL-compatible logic families were manufactured using CMOS or BiCMOS technology rather than TTL.
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) were the mainstay of the industry for many decades. They are useful for rapid breadboard-prototyping and for education and remain available from most manufacturers. The fastest types and very low voltage versions are typically surface-mount only, however.[citation needed]
The first part number in the series, the 7400, is a 14-pin IC containing four two-input NAND gates. Each gate uses two input pins and one output pin, with the remaining two pins being power (+5 V) and ground. This part was made in various through-hole and surface-mount packages, including flat pack and plastic/ceramic dual in-line. Additional characters in a part number identify the package and other variations.
Unlike the older resistor-transistor logic integrated circuits, bipolar TTL gates were unsuitable to be used as analog devices, providing low gain, poor stability, and low input impedance.[7] Special-purpose TTL devices were used to provide interface functions such as Schmitt triggers or monostable multivibrator timing circuits. Inverting gates could be cascaded as a ring oscillator, useful for purposes where high stability was not required.
The 7400 quad 2-input NAND gate was the first product in the series, introduced by Texas Instruments in a military grade metal flat package (5400W) in October 1964. The pin assignment of this early series differed from the de facto standard set by the later series in DIP packages (in particular, ground was connected to pin 11 and the power supply to pin 4, compared to pins 7 and 14 for DIP packages).[5] The extremely popular commercial grade plastic DIP (7400N) followed in the third quarter of 1966.[18]
The 5400 and 7400 series were used in many popular minicomputers in the 1970s and early 1980s. Some models of the DEC PDP-series 'minis' used the 74181 ALU as the main computing element in the CPU. Other examples were the Data General Nova series and Hewlett-Packard 21MX, 1000, and 3000 series.
In 1965, typical quantity-one pricing for the SN5400 (military grade, in ceramic welded flat-pack) was around 22 USD.[19] As of 2007, individual commercial-grade chips in molded epoxy (plastic) packages can be purchased for approximately US$0.25 each, depending on the particular chip.
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.[20]
Many parts in the CMOS HC, AC, AHC, and VHC families are also offered in "T" versions (HCT, ACT, AHCT and VHCT) 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, which are more restrictive than TTL thresholds. Typically, CMOS input thresholds require high-level signals to be at least 70% of Vcc and low-level signals to be at most 30% of Vcc. (TTL has the input high level above 2.0 V and the input low level below 0.8 V, so a TTL high-level signal could be in the forbidden middle range for 5 V CMOS.)
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.[102]
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. Many 74LS ICs can be found in microcomputers and digital consumer electronics manufactured in the 1980s and early 1990s.
For example, "SN5400N" signifies that the part is a 7400-series IC probably manufactured by Texas Instruments ("SN" originally meaning "Semiconductor Network"[104]) using commercial processing, is of the military temperature rating ("54"), and is of the TTL family (absence of a family designator), its function being the quad 2-input NAND gate ("00") implemented in a plastic through-hole DIP package ("N").
Many logic families maintain a consistent use of the device numbers as an aid to designers. Often a part from a different 74x00 subfamily could be substituted ("drop-in replacement") in a circuit, with the same function and pin-out yet more appropriate characteristics for an application (perhaps speed or power consumption), which was a large part of the appeal of the 74C00 series over the competing CD4000B series, for example. But there are a few exceptions where incompatibilities (mainly in pin-out) across the subfamilies occurred, such as:
Some manufacturers, such as Mullard and Siemens, had pin-compatible TTL parts, but with a completely different numbering scheme; however, data sheets identified the 7400-compatible number as an aid to recognition.
At the time the 7400 series was being made, some European manufacturers (that traditionally followed the Pro Electron naming convention), such as Philips/Mullard, produced a series of TTL integrated circuits with part names beginning with FJ. Some examples of FJ series are:
This device contains four independent gates each of which performs the logic NOR function. The 74LS02 is a 14 Pin Quad 2-Input NOR Gate IC. NOR gates utilize advanced silicon-gate CMOS technology to achieve operating speeds similar to HC gates with the low power consumption of standard CMOS integrated circuits. Featured by Sharvi Electronics All gates have buffered outputs, providing high noise immunity and the ability to drive 10 LS-TTL loads. The 74HC logic family is functionally as well as pin-out compatible with the standard 74LS logic family.
This product is known as 7402, 74LS02, 74LS02 Quad 2 Input NOR Gate IC, 74XXX series IC, Component, Integrated Circuits, NOR Gate IC, Quad 2 Input NOR Gate IC, SN74LS02NSR, SN74LS02NS, SN74LS02NSRG4, SN74LS02N, SN74LS02NE4.
I bought a pack of 5 ICs from radioshack. (74LS00, 74LS02, 74LS04, 74LS08, and 74LS32 to be specific). And I can't see to wire them correctly. I've wired pin 7 to ground, pin 14 to 5V(from an Arduino Uno), and nothing comes out of any outputs. What even worse is if I disconnect ground the led does come on. And by using the Arduino to measure voltage, all of the outputs are on. I've wired this perfectly and even checked with this site to make sure: 've also checked to make sure that pin 7 is indeed ground and pin 14 is indeed high with the Arduino. I just can't figure out why none of it is working. What's even worse is all of the ICs are exhibiting the same behavior. And I've tried two different breadboards, with the same result. Any help?
The 74LS family is well past its best-before date. It's a DTL family (pretending to be TTL). As such an 'open' input is interpreted as a logic 1. If you leave both inputs open, and are using a 74LS00, it will do what NAND gates do with two '1' inputs and drive the output low. Ground either of the two inputs to a NAND gate and the output should go high.
In general you will be a lot less frustrated if you always connect every in put to a logic 1 or logic 0, including unused inputs. That will come in especially handy with CMOS (eg. 74HC00) where the inputs can do odd things if you let them float. For TTL families and LSxx, ground or tie inputs high through 1K. For CMOS tie high or low directly or through a resistor.
74ls02 is a member of the 74XXYY IC series. 74ls02 is a 14 pin ic with four NOR gates each gate has two inputs hence it called Quad 2 input nor gate. The IC is functional with all other 74LS logic family and it can be operating with any microcontroller or IC due to its low output compatibility.
For a long time, the original 7400 series was the best choice as ageneral-purpose logic family, and the 7400 family had more members than anyof the offshoot families.However, if you were picking a single "best" logic family today itwould probably have to be the 74LS00 family.This family arguably has the widest manufacturer support and range ofavailable line of components.
The 74LS00 family improves technically on the 7400 family in two key areas:faster speed and lower power consumption.The only limitation of the 74LS00 family compared to the 7400 family is thatthe 74LS00 family can only source half as much current.However part of the current reduction in the 74LS00 family was on inputs,such that a typical 74LS00 family part can drive twenty LS loads (that is,one output can fan out to twenty inputs within the 74LS00 family; comparethis to the 7400 family, which could only drive ten inputs in the samefamily).