Integrated+Circuits

toc 1.5 Process components Identification, function and application of the following process component used in the production of electronic products. 1.14 Units and Calculation = Introduction = . Integrated circuits (IC's) are very important components in today's electronics and can be found in many circuits that are in products that you use everyday, your mobile phone, mp3 player, DVD player, washing machine even your refrigerator and your passport. The are also known as silicon chips and microchips. Integrated circuits contain many transistors and other components in a miniaturized form within a single package or **chip**. There are many different types of integrated circuits both digital and analogue, in common use today. Some of the main advantages to be gained by using IC's are: For example the reduction in weight and size has of components has meant that computers which once filled whole rooms and perform arithmetic and logic operations, can now be housed into a container the size of your hand, and probably smaller!!! The integrated circuits are formed on interlocking layers or wafers of silicon making it possible to create individual electronic components. The full text of the description reads: "How does silicon dioxide (beach sand) become an integrated circuit, one of man's most intricate and finely crafted devices? Growing silicon crystals from a single seed crystal is the most important part of the process. This takes place in a furnace which is heated to about 1,500 degrees Celsius (2,732 degrees Fahrenheit). In the furnace is a container filled with molten silicon and a secondary element such as phosphorous or boron. The seed crystal is dipped into the molten material; it is then withdrawn with a rotating motion, similar to making candles by dipping them in hot wax. Solidifying on the seed, the molten material takes on the same atomic structure as the seed. This molecular symmetry distinguished a single crystal from unstructured or non-symmetrical material. Each finished crystal cylinder is approximately six inches in diameter and about four feet long. Using a high speed diamond edged saw, the cooled glass-like cylinder is then sliced into wafers. All silicon wafers are not exactly the same, each manufacturer's wafer varies in thickness and surface finish due to their unique specifications. It takes about 50 complex steps to convert wafers into integrated circuits. The final step is cutting the wafer into hundreds of tiny circuit chips." http://www.flickr.com/photos/lakupo/30836265/?addedcomment=1#comment72157612338484562
 * 555 IC, monostable & astable circuits
 * Time Period: T = 1.1 RC
 * Frequency: f = 1.44 / (R1 + 2R2) x C
 * weight and space saving
 * low power requirements
 * robustness - they rarely fail if used properly
 * cheap when mass-produced

= 555 Integrated Circuit = The 555 timer is one of the most widely used types of integrated circuits. A semiconductor device that controls various modes of on/off states in electrical systems. By using a 555 IC as an alternative to a transistor or logic gates, reduces the number of components used in a circuit. They are reliable, however it has the disadvantage of needing an amplifier to drive some output devices. Check out the sites from "doctronics" which has recently been updated. http://www.doctronics.co.uk/555.htm

= What the 555 looks like = = What the 555 is used for = = What the 555 is made of = An integrated circuit consists of a silicon chip in a plastic 8-pin package. The circuit contains two comparators, a bistable, resistor, and transistors. It is also available in a dual package which has two 555's on one chip, called a 556. Typical Characteristics: = How the 555 works = The way the 555 works in a circuit depends on the external components connected to the 555. Its two ways of operating are:
 * To switch something on or off at a precise time e.g. 0900hrs.
 * To switch something on or off after a certain time delay.
 * As a pulse generator. e.g. to provide a series of clock pulses for a counter.
 * Maximum supply voltage ||= 16 V ||
 * Maximum output current ||= 200 mA ||
 * Maximum power ||= 600 mW ||
 * Reset Current ||= 0.1 mA ||
 * Trigger voltage ||= 1.6 - 5 V ||
 * As an **astable** (produces a series of pulses)
 * As a **monostable** (produces a single pulse)

= 555 Monostable = The length of the pulse **T** is given approximately by multiplying the value of **R** by **C**. The actual timing formula is: For example:
 * How you use it**:
 * ** T = 1.1 x R x C **
 * ** C = **** 10uF **
 * ** R = **** 100kOhms **
 * ** T = 1.1 x RC **
 * ** T = 1.1 x (100 000 x 0.000 01) **
 * ** T = 1.1 x 1 **
 * ** T = 1.1 seconds **

http://www.doctronics.co.uk/DDE/DDE_04.html

= 555 Astable = If the voltage on the trigger is less than one third of the supply voltage **V**, the output (pin 3) goes high, and pin 7 is disconnected from the ground. When the voltage on the threshold is greater than two thirds of **V** the output goes low,. and pin 7 is grounded
 * How you use it**:

The formula to calculate the frequency is: For example:
 * ** f = 1.44 / (R1 + 2R2) x C **
 * ** R1 =10kOhm **
 * ** R2 = 100kOhm **
 * ** C = 1uF **
 * ** f = 1.44 / (10 000 + 200 000) 0.000 001 **
 * ** f = 1.44 / 210 000 x 0.000 001 **
 * ** f = 1.44 / 0.21 **
 * ** f = 6.9 Hz **

media type="custom" key="2980748" = Notes about the 555 = In both cases, the values of the resistances and capacitor can be changed (using the calculator above) to meet a particular design specification. Using variable resistors and looking at the output on an oscilloscope allows the circuit to be "tuned". It is important to be able to distinguish between a monostable 555 circuit and an astable 555 circuit, learn the pin connections:
 * Pin 3 is always the output
 * Pin 2 is the trigger
 * Pin 6 is the threshold
 * Pin 7 discharge
 * Monostable: Pins 6 & 7 are connected together
 * Astable: Pins 2 & 6 are connected together

= Other ICs = These include microchips and programmable chips for example: PICAXE, and PIC16F628. There are a range of integrated circuits known as comparators or operational amplifiers, or Op Amps for short. To find out more about these IC's return to the Year 10 Electronics page and go to the sections on Op Amp and and PICs.

= Resources = @http://www.willingtons.com/mymac/555_timer_calc.htm []