bab 1 intro to basic electronic & micro system

8/8/2019 Bab 1 INTRO to Basic Electronic & Micro System

1/70

MICROELECTRONIC

DMA 3223oleh

MOHD ROZAINI BIN MD NAFIAH

Email : [email protected]

Tel : 013-2095340

Unit Kurikulum,Bahagian Kemahiran MARA


2/70

DMA 3223 MICROELECTRONIC

What is the meaning of Microelectronic?

What are the advantages of Microelectronic in

automotive application?

Do you know how ABS, VVTi operates?


3/70


4/70

Front / Rear Distribution Right / Left Distribution


5/70

FuelCutControlSystem

A fuel cut control is used to stop the fuel pump once when

any of the SRS airbags is deployed. In this system, theairbag deployment signal from the airbag sensor assembly

is detected by the engine ECU, and it turns OFF the circuit

opening relay. After the fuel cut control has been activated,

turning the ignition switch from OFF to ON cancels the fuel

cut control, and the engine can be restarted.


6/70

Multiplex

Communication

Each ECUs can share their information through CAN BUS wire to reduce wiring


7/70

AssessmentScheme Theory Test 1 10%

Practical test 1 10%

Theory Test 2 10 % Practical test 2 10%

Assignment (p1) 10%

Assigment (p2) 10%

Final Exam 40 %

CARRY MARKS 60%


8/70

Topic1. Introduction to Basic Electronic and Microcomputer System

i-Diode, Zener Diode and LEDii-Transistor

iii-Capacitor

iv-Thermistor

v-Photoconductive Cell

vi-Logic Gate

2. An introduction of Microcomputer

i-Basic layout of microcomputer

ii-Central Processing Unit CPU

iii-Temporary Storage Unitiv-Arithmetic Logic Unit (ALU)

v-Input and Output Interface


9/70

3. Programming and Computer Language

i-Digital principalii-Consept of Binary

iii-Bit and Bytes

iv-Random Access Memory RAM

v-Read Only Memory ROM

vi-Data Buses

vii-Adress Busesviii-Control Buses

4. Microelectronic System

i-Programming

ii-Measurementiii-Sensors and Actuator

iv-New developments in Microelectronic

v-Diagnostic-Electronics, Sensors and Actuators


10/70

Electronicin Automotive


11/70

1.

DiodeWhat is covered in this chapter:

1. Semiconductor principles

2. Diodes;Junction, Zener

3. Other two-lead devices: LED, LDR,photodiode,

thermistor


12/70

Semic

onduct

or

Pri

nciple

s A semiconductor is a material which has an electricalresistance value lower than insulator and higher than a

conductor

Semiconductor materials such as Silicon and Germanium,

have an atomic structure which behaves differently from

material that are good conductors

Electrical current was produced by the random drift of free

electrons.

In insulator, and partly in semiconductor, electron drift is

limited because there are relatively free electron available

that are not tightly bounded to their atomic home


13/70


14/70

Cont..

Intrinsic Semiconductor- semiconductors in their purestform

Extrinsic Semiconductor-semiconductors with other atomsmixed in. These other atoms are called impurityatoms.The process of adding impurity atoms is called doping.The doping alters the characteristics of the semiconductor,mainly its conductivity.

At room temperature (about 25r C), an intrinsicsemiconductor acts more like an insulator than aconductor.

The conductivity of an extrinsic semiconductor is greater

than that of an intrinsic semiconductor. The level of conductivity is dependent mainly of the

number of impurity atoms that have been added during thedoping process.


15/70

AtomicTheory

The atom has been shown to contain threebasic particles: theprotons and neutrons that

make up the nucleus (core) of the atom and

electrons that orbit about the nucleus. The

basic model of the atom, called the Bohr

model


16/70

Cont..

The orbital paths, or shell, are identified usingthe laterK through Q. The innermost shell isthe K shell, followed by the L shell, and so on.The outermost shell for a given atom is calledthe valence shell. The valence shell of an atomis critical because it determines the conductivityof the atom.

K shell = 2 x 12 = 2 electrons

L shell = 2 x 22 = 8 electrons

M shell = 2 x 32 = 18 electrons


17/70

Valence Electron

The valence shell of an atom can containup to eight electrons. The conductivity ofthe atoms depends on the number of

electrons that are in the valence shell.When an atom has one valenceelectrons, it is a nearly perfect conductor.When an atom has eight valenceelectrons, the valence shell is said to be

complete, and the atom is an insulator.Therefore, conductivity decreases withan increase in the number ofvalenceelectrons.


18/70

Cont..

Semiconductors are atoms that containfour valence electrons.

Because the number of valence electrons

in a semiconductor is halfway between one

(for and conductor) and eight (for aninsulator),

a semiconductor atom is neither a good

conductor nor a good insulator.

Three of the most commonly used

semiconductor materials are Silicon(Si),

Germanium (Ge) and Carbon (C)


19/70

Semiconductoratoms


20/70

CovalentBonding

Covalent bondingis the method by whichatoms complete their valence shells by sharing

valence electrons with other atoms


21/70

Cont..

A silicon atom with its four valence electrons produces thecovalent bonds that hold the atoms together, because

each shared electron is attracted equally by the two

adjacent atoms which share it.

The results of this bonding are as follows:

The atoms are held together, forming a solid substance.

The atoms are all electrically stable because their valence

shells are complete.

The complete valence shells course the silicon to act as

an insulator. Thus, pure (intrinsic) silicon is a very poorconductor. The same principle holds true for intrinsic

germanium.


22/70

ELECTRON AND HOLE CURRENT

When a voltage is applied across a piece of intrinsic silicon,the thermally generated free electrons in the conduction

band, which are free to move randomly in the crystal

structure, are now easily attracted toward the positive end.

This movement of free electrons is one type of current in asemiconductor material and is called electron current.


23/70

Cont.

Another type of current occurs at the valencelevel, where the holes created by the free

electron exist.

Electrons remaining in the valence band are still

attached to their atoms and are not free to moverandomly in the crystal structure as are the free

electrons.

However, a valence electron can move into a

nearby hole, with little change in its energy level,thus leaving another hole where it came from.

Effectively the hole has moved from one place to

another in the crystal structure. This is called

hole current.


24/70

Hole current in siliconHole current in silicon


25/70

DOPING

Doping is the process of adding impurity atomsto intrinsic silicon or germanium to improve theconductivity of the semiconductor. Since a dopedsemiconductor is no longer pure, it is called anextrinsic semiconductor.

Two element types are used for doping, trivalentand pentavalent. A trivalentelement is one thathas three valence electrons. Example Aluminum,Indium and Boron.

Apentavalentelement is one that has fivevalence electrons. Example Phosphorus, Arsenicand Antimony.


26/70

Cont

When pentavalent impurities are used, theresulting material is called an n-type material.Since the pentavalent atoms in the n materialare giving up electrons, they are often referredto as donoratoms.

When trivalent atoms are added to intrinsicsemiconductors, the resulting material is calledap-type material.

The trivalent atoms, on the other hand, areaccepting electrons from the pentavalent atomsand thus are referred to as acceptoratoms.


27/70

N-TYPE SEMICONDUCTOR

To increase the number of conduction bandelectrons in pure silicon, pentavalent impurityatoms are added.

These are atoms with five valence electrons,

such as Arsenic, Phosphorus and Antimony.This extra electron becomes a conductionelectron because it is not attached to any atom.

The number of conduction electrons can be

controlled by the amount of impurity added tothe silicon.


28/70


29/70

Pentavalentimpurityatoms in a silicon crystal


30/70

MAJORITY AND MINORITYCARRIERS

Since most of the current carriers are electrons,

silicon (or germanium) doped with pentavalent

atoms is an n-type semiconductor material (the n

stands for the negative charge on an electron).

The electrons are called the majority carriers in

n-type material.Although the majority of current

carriers in n-type material are electrons, there are

also a few holes that are created when electron-

hole pairs are thermally generated. These holes are not produced by the addition of the

pentavalent impurity atoms. Holes in an n-type

materialare called minority carriers.


31/70

P-TYPE SEMICONDUCTOR

To increase the number of holes in pure silicon,trivalent impurity atoms are added. These are atoms

with three valence electron such Aluminum, Boron and

Gallium.

As illustrated in Figure, each trivalent atom (Boron, inthis case) forms covalent bonds with four adjacent

silicon atoms.

All three of the Boron atoms valence electron is used

in the covalent bonds; and, since four electrons are

required, a hole is formed with each trivalent atom. The

number of holes can be controlled by the amount of

trivalent impurity added to the silicon.


32/70

Trivalentimpurityatomin a silicon crystal. A

Boron (A) impurityatomis shown in thecenter


33/70

MAJORITY AND MINORITY CARRIERS

Since most of the current carriers are holes, silicon (or

germanium) doped with trivalent atoms is called a p-

type semiconductor material.

Holes can be thought of as positive charges because

the absence of an electron leaves a net positive charge

on the atom. The holes are the majority carriers in p-type material.

Although the majority of current carriers in p-type

material are holes, there are also a few free electrons

that are created when electron-hole pairs are thermallygenerated.

These free electrons are not produced by the addition of

the trivalent impurity atoms. Electrons in p-type

materialare the minority carriers.


34/70

PN JUNCTIONS

Basic PN structure in a diode at the instant of junction formation

When a piece of silicon is doped so that half is n-type and the otherhalf is p-type, a PNjunction is formed between the two regions.

A device formed in this way is known as a semiconductor diode. The N region

has many conduction electrons, and the P region has many holes


35/70

THE DEPLETION LAYER

A PN junction becomes useful when we are able to

control the width of the depletion layer. By controllingthe width of the depletion layer, we are able to control

the resistance of the PN junction and thus the amount

of current that can pass through the device.


36/70

FORWARD-BIASED


37/70

External voltage pulls majority current carriers away from the

pn junction.


38/70

DIODE The diode is a single pn junction device

with conductive contacts and wire leadsconnected to each region, as shown in.One half of the diode is an n-typesemiconductor and the other half is a p-type semiconductor

The n region is called the cathode andthe p region is called the anode.The"arrow" in the symbol points in thedirection of conventional current(opposite the electron flow).


39/70

Diodes


40/70

Diodeanalogy


41/70

DIODE APPLICATIONS Basically, a diode functions in the same way as a polarity-operated

switch. When forwardbiased, it presents a relatively low resistanceand acts like a closed switch. While, reverse-biased it presents ahigh resistance and acts like an open switch

The following list summarizes the main uses for diodes:

i. Power-supply rectifier

This function is converting ac input from the 60-Hz power line to dc

output. One diode is used for a half-wave rectifier. The full-waverectifier needs two diodes.

ii. Signal detector

The detector circuit uses a diode to rectify a modulated signal inorder to recover the modulating signal.

iii. Digital logic gate

In these circuits, the diode functions as a switch. It is on when thediode conducts and off without conduction.


42/70

Diode: RectifierBridge


43/70

DIODE IDENTIFICATION AND RATING

It is important to identify correctlythe anode and cathode lead endsof the diode for proper connectioninto circuits.

Some diodes have the diodesymbol printed on the case.Cylinder-shaped diodes use a dark

band for lead identification. The lead end nearest to the band is

the cathode and the lead on theopposite end is the anode

Diodes are rated for the maximumcurrent they can safely conduct inthe forward-bias direction.Exceeding this current rating willcause the diode to overheat andcan permanently damage it


44/70

FORWARD AND REVERSE BIAS OFTHE DIODE A diode is forward-biasedwhen

the positive terminal of thevoltage source is connected to

the anode. The negative

terminal of the source is

connectedto the cathode

The forward current, (IF), is from

anode to cathode as indicated.

The forward voltage drop (VF)

due to the barrier potential is

from positive at the anode tonegative at the cathode


45/70

A diode is reverse biasedwhen a negative terminal is

connected to the anode, and

the positive terminal is

connected to the cathode. The current is zero

(neglecting the small reverse

current).


46/70

CURRENTVOLTAGE (I-V) CHARACTERISTICCURVE OFA PN JUNCTION


47/70

THE IDEAL DIODE

The ideal diode has thecharacteristic of an open

switch when it is reverse

biased and those of a

closed switch when

forward biased.


48/70

When reverse diode (open switch)

The diode will have infinite resistance. The diode will not pass current.

The diode will drop the entire applied voltage acrossits terminals

When forward biased (closed switch)

The diode will have no resistance.

The diode will have no control over the currentthrough it.

The diode will have no voltage drop across itsterminals.


49/70

TYPE OFDIODES

ZENER DIODES

A zener diode is a special diode that has beenoptimized for operation in the breakdown region.These devices are unlike ordinary diode, whichare intended never to be operated at or nearbreakdown

Voltage regulation is perhaps the most commonapplication of a zener diode. The zener diode isconnected parallel with the load of the powersupply. The zener voltage remains constantdespite load current variations

Zener diode allows current to flow in the forward

direction. However, it differs from an ordinarydiode in that its reverse-direction break-downvoltage is much lower than that of an ordinaryrectifying diode


50/70

The large number of extra current-

carriers allows the zener diode to

conduct current in the reverse

direction. This reverse-bias current

would destroy a normal diode, but

the zener is made to operate this

way.

Zener diodes can function asvoltage-sensitive switches because

they allow current to flow in the

reverse direction only when a

specfified level of reverse voltage is

reached

Zener diodes are often used as part

of automotive voltage-regulator

circuits. A simple zener diode

regulator circuit are such as below:


51/70

Zenerdiodeanalogy


52/70

A 5-V zener diode is connectedin series with a resistor R, to thevariable DC input voltage. Thisinput voltage is connected sothat the zener diode is reverse-biased. The series resistor (R,) isrequired to drop all the inputvoltage not dropped across the

zener diode As the input voltage is increased

from 0 V, the voltage across thezener diode increases until the 5-V zener voltage is reached. Atthis point the zener diode

conducts and maintains aconstant 5-V output as the inputvoltage varies from 5 to 9 V.


53/70

Volt-Ampere CharacteristicCurve


54/70


55/70

Singlephasehalf-waverectifiercircuit


56/70

Singlephasefull-wave bridgerectifiercircuit


57/70

Three-phasethree-waverectifiercircuit


58/70

It is necessary to convert the alternating

current from the alternator into direct

current before it can be used to charge

the battery and operate other circuits of

the vehicle. The automotive alternator

uses a six-diode, three-phase bridgerectifier circuit to accomplish this. Figure

shows the two typical configurations

used; wye-wound statorand delta-

wounnd stator.


59/70

Typicalrectifiercircuitconfiguration


60/70

LIGHT EMITTING DIODE (LED)

A light emitting diode (LED) is a specialsemiconductor diode designed specificallyto emit light when current flow s through it

When forward-biased, the energy of theelectrons flowing through the resistance ofthe potential barrier is converted directly to

light energy. Because the LED is a diode, current will

flow only when the LED is connected inforward-bias.

The diode itself is only a part of the LED

package. It also requires leads and aplastic lens to diffuse the light.


61/70


62/70


63/70

Use this formula to determine theresistance of the series droppingresistor Rs.

Rs = VIN - VLED

ILED

= 12 V - 1.5 V

22 mA

= 0.477 k

= 477 (470 is the closeststandard resistance value)


64/70

The main advantages of using

an LED as a light source

rather than an ordinary lightbulb are a much lower power

consumption and a much

higher life expectancy.

LEDs are used in someautomotive circuits for

indicator lights and digital

displays.

LEDs can be used as single

indicator lights or can be

arranged to display an alpha

or numeric character. They

are available in red, yellow

and green


65/70

Seven-segmentcommon anode LEDdisplay


66/70

For this application, the LEDs are arranged inseven separate segments.

When the correct voltages are applied to theLEDs, one or more of the segments will light upto permit the display of digits 0 to 9. With the

switch closed, segments A, B, C, D and G lightup to form the number 3.

An LED is not well suited for automotivedisplay use because of its low brightness.

Although it can be seen easily in darkness, it is

rather difficult to see in bright sunlight. It alsorequires more electrical power to operatecompared with other displays


67/70

LIQUID CRYSTAL DISPLAY (LCD)


68/70

Liquid crystal displays (LCDs) scatter light rather than generate it. As aresult, they have the lowest power drain of any display.

Their low power consumption makes them ideally suited for use inbattery-operated devices such as digital multi-meters.

Other advantages over LED-type displays include better readability insunlight and adaptability for use with more complex display patterns.

A thin layer of transparent liquid crystal or polarized fluid is sandwichedbetween two glass plates. The display has electrodes placed on theglass.

When there is no voltage applied, light cannot pass through the fluidbecause of the random arrangement of light slots in the fluid.

Selectively applying voltage to the segment contacts produces anelectrostatic field, which forces the liquid crystal molecules within theelectrostatic field to rearrange themselves.

As a result, light striking this part of the display is scattered, causing the

segments to appear black on a silvery background. Although the LCD can be read in the daytime (Just the Opposite of the

LED), small lamps must be used inside the display for it to be seen atnight. Another limitation of the LCD for automotive applications is thatthe display does not work well at the low temperatures encounteredduring winter driving in some areas.

Assignment


69/70

g1. Name three popular semiconductor devices.

2. What is the electron valence for Si and Ge?

3. How is a pure semiconductor crystal made to conductelectricity better.

4. Explain the process of producing N-type semiconductormaterials.

5. Explain theWhat is the most commonly used semiconductormaterial.

6. process of producing P-type semiconductor materials.

7. Compare the way electricity is conducted in N-type and P-type semiconductors.

8. Is the Si doped with phosphorus, its goes to N-type or P-type?

9. True or False? Hole current is in the same direction aselectron flow.

10. Is forward current a flow of majority or minority chargecarries?

11. How does current flow through a PN junction or diode.

12. What determines whether a diode is forward or reversebiased?

13. Draw the symbol for a diode and correctly label its leads.

14. State two ways in which diodes are rated.


70/70

bab 1 intro to basic electronic & micro system

Documents