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Introduction to Electrical Engineering II Prof. Dr. Hasan H. Erkaya Eskiehir Osmangazi University 2008 Logic Systems and Gates Slide 2 Systems Analog System: a system in which variables are allowed to take any value within a range: Slide 3 Analog Systems An electrical circuit: Slide 4 Analog Systems Another electrical analog circuit: Slide 5 Systems Digital System: a system in which variables are allowed to take only predetermined finite number of values Slide 6 Digital Systems Slide 7 Binary numbers are used to represent most digital systems. Binary digit = bit ( 0, 1) 8 bits side by side = 1 byte (e.g. 10011011) Slide 8 Binary Systems A physical variable is used to represent binary values: e.g. a voltage or a current Slide 9 Binary Systems Analog to Digital Converter Slide 10 ADC Slide 11 Binary Systems Digital to Analog Converter Slide 12 DAC Slide 13 Why bother with digital systems? Digital sistems can process information a lot easier than analog sistems Digital computer is much more skilful than the analog computer Is there an analog computer, too? (Yes! It can take derivative, integral and do other operations) Slide 14 Boolean Algebra Basic Operations AND OR NOT Gates are used for these operations Slide 15 AND gate A. B Slide 16 OR gate A+B Slide 17 NOT gate (inverter) A _ Slide 18 Combined Gates AND + NOT = NAND OR + NOT = NOR Slide 19 Exclusive OR Slide 20 Exclusive NOR Slide 21 Logic Functions Slide 22 Truth Table ABCF 0000 0011 010x 011x 100x 101x 1101 111x Slide 23 Karnaugh Maps Slide 24 Slide 25 K-maps Slide 26 Building the Circuit Often NAND gates are used to implement the logic functions Slide 27 7400 series ICs 7400: Quad 2-input NAND Gate 7401: Quad 2-input NAND Gate with Open Collector Outputs 7402: Quad 2-input NOR Gate 7403: Quad 2-input NAND Gate with Open Collector Outputs (different pinout than 7401) 7404: Hex Inverter 7405: Hex Inverter with Open Collector Outputs 7406: Hex Inverter Buffer/Driver with 30V Open Collector Outputs 7407: Hex Buffer/Driver with 30V Open Collector Outputs 7408: Quad 2-input AND Gate 7409: Quad 2-input AND Gate with Open Collector Outputs Slide 28 7400 series ICs 7410: Triple 3-input NAND GateNAND Gate 7411: Triple 3-input AND GateAND Gate 7412: Triple 3-input NAND Gate with Open Collector OutputsNAND GateOpen Collector 7413: Dual Schmitt trigger 4-input NAND GateSchmitt triggerNAND Gate 7414: Hex Schmitt trigger InverterSchmitt triggerInverter 7415: Triple 3-input AND Gate with Open Collector OutputsAND GateOpen Collector 7416: Hex Inverter Buffer/Driver with 15V Open Collector OutputsInverterOpen Collector 7417: Hex Buffer/Driver with 15V Open Collector OutputsOpen Collector 7419: Hex Schmitt trigger InverterSchmitt triggerInverter 7420: Dual 4-input NAND GateNAND Gate 7421: Dual 4-input AND GateAND Gate 7422: Dual 4-Input NAND Gate with Open Collector OutputsNAND GateOpen Collector 7423: Expandable Dual 4-input NOR Gate with StrobeNOR Gate 7424: Quad 2-input NAND Gate gates with Schmitt-trigger line-receiver inputs.NAND Gate 7425: Dual 4-input NOR Gate with StrobeNOR Gate Slide 29 7400 series ICs Flip-flops Counters Registers Memory devices and more Slide 30 7400 quad 2-input NAND gates Slide 31 7404 hex inverters Slide 32 7408 Quad 2-input AND gates. Slide 33 7410 Triple 3-input NAND gates Slide 34 8-input NAND gate Slide 35 7432 Quad 2-input OR gates Slide 36 Logic Circuits Combinational Logic: output is determined by inputs only Sequential Logic: output depends on the inputs and history it contains some memory device to remember the past Slide 37 Logic Systems and Gates I hope this presentation gave you a glimpse of the logic systems and digital circuits. You will have plenty of experience with digital circuits in Digital Systems I, II and Lab courses. End of the presentation