This document discusses combinational logic circuits. It defines a combinational circuit as consisting of input variables, logic gates, and output variables. It then lists common applications of combinational circuits such as multiplexers, demultiplexers, encoders, decoders, and half/full adders. The document provides procedures for analyzing combinational logic circuits by labeling gate outputs and substituting Boolean functions to determine the overall output functions. An example circuit is analyzed using these steps. Common combinational logic circuits like multiplexers, decoders, and adders are also described.

1. Combinational
Login Circuit

2. Combinational Logic
● Logic circuits for digital systems may be
combinational or sequential.
● A combinational circuit consists of input variables,
logic gates, and output variables.
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5. Combinational Logic Circuits
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Combinational
Logic Circuits

6. Applications of combinational circuits are
1. Multiplexer
2. Demultiplexer
3. Encoder
4. Decoder
5. Seven Segment Decoder
6. Half Adder
7. Full Adder
8. Binary Adder
9. Half Subtracter
10. Full Subtracter
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7. 4-2. Analysis procedure
● To obtain the output Boolean functions from a
logic diagram, proceed as follows:
1. Label all gate outputs that are a function of input variables
with arbitrary symbols. Determine the Boolean functions
for each gate output.
2. Label the gates that are a function of input variables and
previously labeled gates with other arbitrary symbols. Find
the Boolean functions for these gates.
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8. 4-2. Analysis procedure
3. Repeat the process outlined in step 2 until the outputs of
the circuit are obtained.
4. By repeated substitution of previously defined functions,
obtain the output Boolean functions in terms of input
variables.
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T1 = A + B + C; T2 = ABC;
F2 = AB + AC + BC;
T3 = F2’T1;
F1 = T3 + T2
F1 = T3 + T2 = F2’T1 + ABC = A’BC’ + A’B’C + AB’C’ + ABC

9. Example
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10. Derive truth table from logic diagram
● We can derive the truth table in Table 4-1 by using
the circuit of Fig.4-2.
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11. Adder
● Half adder
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12. ● Full adder
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13. Multiplexer & Demultiplexer
● Multiplexer & Demultiplexer
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14. ● Multiplexer
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15. ● Demultiplexer
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16. Encoder & Decoder
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17. Seven segment Decoder
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18. Example of Combinational Logic Circuits
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Design of logic circuit for control of water pumping
Design of building alarm device

19. Thanks
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