Page 44 - CITS - Electronic Mechanic - TT - 2024
P. 44
ELECTRONICS MECHANIC - CITS
Boolean Equation
Q0 = D1 + D3 + D5 + D7
Q1 = D2 + D3 + D6 + D7
Q2 = D4 + D5 + D6 + D7
Decoder
• Decoder is a device which does the reverse operation of Encoder. It is a combinational circuit that converts
binary information from ‘n’ input lines to a maximum of ‘2n’ unique output lines.
• Decoder is identical to a demultiplexer without any data input.
• E.g.: 2 to 4 Decoder, 3 to 8 Decoder, BCD to Seven Segment Decoder
2 to 4 Line Decoder
• I0 & I1 are two inputs whereas y3, y2, y1 & y0 are four outputs.
• The truth table shows that each output is ‘1’ for only a specific combination of inputs.
Boolen Equation
y0 = I̅ 1I̅ 0;
y1= I1I0;
y2 = I1I̅ 0;
y3= I1I0
Truth Table
Working
• According to the truth table, when I1I0=00, the output Y0 is set to ‘1’, others are‘0’
• When I1I0=01, the output Y1 is set to ‘1’, others are‘0’
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CITS : E & H - Electronics Mechanic - Lesson 9 - 29
