Chapter 1 Electronic & Microprocessor

8/12/2019 Chapter 1 Electronic & Microprocessor

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ELECTRONIC &

MICROPROCESSOR(ECE 590)

Fakulti KejuruteraanMekanikal


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PROGRAM OUTCOME Ability to acquire and apply knowledge ofengineering fundamentals.

OBJECTIVETo develop knowledge in the operation simple electroniccircuits : diode and BJTTo learn and develop knowledge in logic devices andcircuitsTo learn microprocessor system, programming andsimple interface techniques.


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CHAPTER 1: CIRCUIT THEORY

What is the meaning of voltage andcurrent? Electrical components Ohms Law Kirchoffs Laws Introduction to Electronic System


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What is voltage and current?

Voltage is the measure of specific potentialenergy (potential energy per unit charge)between two locations. When a voltage source is connected to a circuit,the voltage will cause a uniform flow of electronsthrough that circuit called a current .

In a single (one loop) circuit, the amount ofcurrent at any point is the same as the amountof current at any other point.


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Example (concept of voltage and

current)


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Electrical Components

ResistorDiode

TransistorCapacitorInductor


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Ohms Law

Ohms Law simply states that cu rrent in ares i s t ive c i rcu i t i s d i rec t ly prop or t iona l to i t s

app l ied vol tage and inversely p rop or t iona l toi ts resis tance.


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Example


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Cont..

As with all circuit elements, we need to know how thecurrent through and voltage across the device are relatedMaterials with a linear relationship satisfy Ohms law: v= mi

The slope, m, is equal to the resistance of the elementOhms Law: v = iR


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Short Circuit as Zero Resistance

An element (or wire) with R = 0 is called ashort circuitOften just drawn as a wire (line)


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R= (infiniti)


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Voltage Symbols


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I

Vs

+ V R 2 - +

V R N-

+ V R 1 -

R 1

R N

R 3

R 2

- V R 3 +

Series Resistor

Total Resistance: R T = R 1 + R 2 + R 3 + .. + R N The supplied power = Total power dissipated by resistors

PT = P R1 + P R2 + P R3 + .. + P RN

T

S

R

V I


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R NR 2R 1V s

I T

I 3I 2I 1

The total current is equal to the total sum of the branch current,

I T = I 1 + I 2 + .. + I N

N T R R R R

1.......

111

21

Parallel Resistor


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Example


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0.2941mA

9.66V4k

6.76V

1.324mA

Exercise:


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Kirchoffs Laws The foundation of circuit analysis is

The defining equations for circuit elements (e.g. Ohms law) Kirchoffs current law (KCL)

Kirchoffs voltage law (KVL) The defining equations tell us how the voltage and currentwithin a circuit element are relatedKirchoffs laws tell us how the voltages and currents indifferent branches are related


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Kirchoffs Current Law (KCL)

Kirchoffs Current Law (KCL) : the algebraic sumof currents entering a node (or a closed boundary) is

zeroThe sum of currents entering a node is equal to thesum of the currents leaving a node


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Kirchoffs Current Law for Boundaries


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Example


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Kirchoffs Voltage Law (KVL)

Kirchoffs Voltage Law (KVL) : the algebraic sum of

voltages around a closed path (or loop) is zeroVoltage drop at each element must be same with thevoltage supply.

v 4 + v 1 + v 2 + v 3 = 0


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Example

Consider Figure 5.2 with the followingParameters:

V 1 = 15 V

V 2 = 7 V R 1 = 20 R 2 = 5 R 3 = 10

Find current through R 3 using Kirchhoff'sVoltage Law.

Solution:

From Loop 1 we get: V 1 V R3 V R1 = 0

From Loop 2 we get: V 2 V R3 V R2 = 0


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Continue..

..... (1)

and

V 2 + ( I 1 I 2) * R 3 I 2 * R 2 = 0

... (2)

By equating above (1) and (2) we caneliminate I 2 and hence get the following:

... (3)

It is clear that: from (3)

Substitute the Above Result into (2)

The Negative sign for I R 3 only tells us thatCurrent I R 3 flows in the same direction to I 2 direction.


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Thevenins Theorem Thevenin's Theorem states that it is possible to simplify anylinear circuit, no matter how complex, to an equivalent circuitwith just a single voltage source and series resistanceconnected to a load


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Example

Step 0: The original circuit

Step 1: Calculating the equivalent outputvoltage


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Continue..

Step 2: Calculating the equivalentresistance Step 3: The equivalent circuit


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Voltage Divider Rule

The voltage divider is useful indetermining the voltage drop across a

resistor within a series circuit.


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Example Analyze a simple series circuit, determiningthe voltage drops across individualresistors


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Current Divider RuleCurrent Divider Rule is useful indetermining the current flow through onebranch of parallel circuit.

R 1V s

I T

I 2I 1

+

V 1-

+

V 2-

T R

R

21

21

R I

T R

R

21

12

R I


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Example Analyze a simple parallel circuit, determining the branch currentsthrough individual resistors

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Chapter 1 Electronic & Microprocessor