1 Electronic Circuits TRANSISTOR PRINCIPLES & APPLICATIONS.
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Transcript of 1 Electronic Circuits TRANSISTOR PRINCIPLES & APPLICATIONS.
1
Electronic Circuits
TRANSISTOR PRINCIPLES & APPLICATIONS
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Electronics
Principles & ApplicationsSixth Edition
Chapter 5Transistors
Electronic Circuits
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Transistors as a Solid State SwitchOBJECTIVES
Transistors as a Solid State SwitchOBJECTIVES
Describe how a transistor can be used as a switch.Determine if a transistor is turning a circuit on or off using voltage measurements.Construct a solid-state switching circuit.Measure circuit voltages in a transistor switching circuit.
Describe how a transistor can be used as a switch.Determine if a transistor is turning a circuit on or off using voltage measurements.Construct a solid-state switching circuit.Measure circuit voltages in a transistor switching circuit.
Electronic Circuits
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How do transistor switches work?How do transistor switches work?Can be viewed as solid state relays:they are either ON or they are OFF.
BJT switches are characterized by:
high base current (or no base current)
low resistance from collector to emitter(or very high resistance)
low collector dissipationPC = VCE x IC
PC = 0 x IC = 0 W(or PC = VCE x 0 = 0 W)
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LOADLOADLOAD
DRIVER
The driver output is zero volts, IB = 0 and ILOAD = 0The driver output is positive, IB > 0 and the load is onThe driver output is zero volts, IB = 0 and the load is off
RCE @ WRCE @ 0 WRCE @ W
NPN SWITCH
Electronic Circuits
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LOAD
DRIVER
The driver output is off (high Z): the resistorpulls the base voltage up so that VBE = 0
PNP SWITCH
The driver output goes low: the voltage dropacross the resistor makes VBE negative
The driver output is off (high Z): the resistorpulls the base voltage up so that VBE = 0
LOADLOAD
Electronic Circuits
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PNP SWITCH WITH NPN DRIVER
LOADLOADLOAD
Electronic Circuits
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A
B
C
D
A B C D
STEPPER MOTOR
Enhancement modepower MOSFETs
used as switches
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Transistors as a Solid State SwitchTransistors as a Solid State Switch
Describe how a transistor can be used as a switch.Determine if a transistor is turning a circuit on or off using voltage measurements.Construct a solid-state switching circuit.Measure circuit voltages in a transistor switching circuit.
Describe how a transistor can be used as a switch.Determine if a transistor is turning a circuit on or off using voltage measurements.Construct a solid-state switching circuit.Measure circuit voltages in a transistor switching circuit.
Electronic Circuits