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Digital System
清 教授
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Binary for Digital
• Digital Binary: define different voltage
levels for state o and 1 in positive logic ornegative logic
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Digital Circuit Design
• Digital circuit is designed using circuit
combination families
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Digital Circuit
• Digital circuits require a solid ground as a
reference for lower level state• Positive logic 5V = logic 1, 0V=logic 0
• Negative logic 5V = logic 0, 0V = logic 1
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TTL
• Transistor-Transistor Logic circuit is
composed of transistors
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CMOS
• Complementary Metal Oxide
Semiconductors for high speed and low
power consumption
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IC Package
• Integrated Circuit is packed for different
assembly processes
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IC Pin Assignment
• A small dip dot on its
top, a semi-spherecut on the short side
• Starting from the dot,
as pin 1 in counterclockwise sequence
• SN= company• N= package
• 7419= made in year1974 in 19th week
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IC Pin Assignment
• Logic combination is
designed on acommon
arrangement
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PCB Design
• All electronic circuits are mounted on
printed circuit boards by insertingcomponents through the pin holes and
then soldering on the back side
• PCB circuit is designed on the back side
• What should you pay attention to?
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BCD
• Binary coded Decimal counts 0/1 for 0-9
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4-Bit Coding
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Binary Numbering
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What we need to know
• Digital circuits are generally very high
impedance system that requires low power • It relies on correct states to express each
condition• Sometimes, a state is lasting for a long
period, however, it might be very short in
time frame referring to a digital clock
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How to Build Digital Circuit
• Correctly identify the logic concept of your
circuit• Design a circuit plan
• Choose appropriate circuit components• Build a circuit on bread board firstly to
check this circuit design is correct• Then build PCB for final fabrication
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Tool to Use
• The laboratory offers circuit components to
build your circuit on bread boards,connecting through short wires using
appropriate tools
• You need power supply to activate your
circuit, and read circuit waveforms from
oscilloscope by assisting functiongenerator
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Components
• Most ICs are also passive components
which receive a signal and consume itsfeeding energy
• Active components also consume energy,but may create or change signals into
higher level of voltage or current, termed
as amplification
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Components
• You may need passive components such
as RLC, resistor, inductor, capacitor • R normally is 1/2W or 1/4 W from 0.1Ω to
100 MΩ• L has quite varieties in copper winding
mostly from 10μh~10 mh
• C is specified for DC or AC n different
capacitance from pf~5000μf
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Components
• Logic ICs, LEDs, displays, switches in our
assignments are all passive components
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Components
• You will use active components such as
different kinds of transistors, FETs, solarcells, batteries, that offer energy or change
feeding signals
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Future Work
• In this laboratory course, you just learn
circuit building and tests from fourassignments, including some minor design
effort
• In the future, you may learn
microprocessor to send commands into
digital circuits for your objectives
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Boolean Algebra
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D
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D
• D
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D
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