Answer to Question #244180 in Electrical Engineering for laurebel

Question

By using the 74LS139 IC, DIP switches and 4 LEDs, draw and construct the 2-to-4 line decoder

Answer 1

The decoder, like the multiplexer circuit, is not limited to a single address line and hence can have more than two outputs (with two, three, or four address lines). The decoder circuit can decode a binary number of 2, 3, or 4 bits, as well as up to 4, 8, or 16 time-multiplexed signals.

This circuit acts as a decoder, taking an n-bit binary number and producing an output on one of the 2n output lines. As a result, it is often defined by the number of addressing i/p lines and the number of data o/p lines. Two 2-4 line circuits, a 3-8 line circuit, or a 4-16 line decoder circuit are examples of typical decoder ICs. The 4-10 line decoders, which are intended to convert a Binary Coded Decimal (BCD) input to a 0-9 range output, are an exception to the circuit's binary nature.

This sort of decoder has two inputs, A0 and A1, and four outputs, indicated as D0, D1, D2, and D3. As shown in the truth table below, one o/p line is switched on for each input combination.