Decoder Circuit using IC 7447

We already published the article about 3 to 8 decoder circuit using basic logic gates(AND, OR, NOT Gates) with Seven Segment display as well as LEDs. That circuit was very complex but that gives you a good knowledge about Decoder Circuit. In this article, we are going to know BCD to Seven Segment Display Decoder(using a single IC) with examples and circuit diagrams.

BCD means Binary Coded Decimal. We can represent each of the decimal numbers by its four-bit binary numbers.

To drive a Seven Segment Display we need BCD to Seven Segment Display Decoder circuit. So here we used an IC 74LS47 for this work.

So before making the circuit let's know about the IC 74LS47.

Pin Diagram of IC 74LS47 :

• A0, A1, A2, A3 are the BCD input pins.
• LT - for display test
• RBO, RBI is the Ripple blanking output and Ripple blanking Input pins respectively.
• a, b, c, d, e, f, g are the outputs for seven segment display.

Now let's make the circuit with a Common Anode Seven Segment Display,

We have four pins to give BCD inputs so we can display from 0 to 15 numbers but we have need two seven segment display. In the below circuit diagram one seven segment display is used so here 0 to 9 numbers can be shown.

The truth table is given below for the circuit,

 INPUTS OUTPUTS LT RBO A3 A2 A1 A0 a b c d e f g DecimalNumbershow indisplay 0 0 0 0 0 0 1 1 1 1 1 1 0 0 0 0 0 0 0 1 0 1 1 0 0 0 0 1 0 0 0 0 1 0 1 1 0 1 1 0 1 2 0 0 0 0 1 1 1 1 1 1 0 0 1 3 0 0 0 1 0 0 0 1 1 0 0 1 1 4 0 0 0 1 0 1 1 0 1 1 0 1 1 5 0 0 0 1 1 0 1 0 1 1 1 1 1 6 0 0 0 1 1 1 1 1 1 0 0 0 0 7 0 0 1 0 0 0 1 1 1 1 1 1 1 8 0 0 1 0 0 1 1 1 1 1 0 1 1 9

Circuit diagram of Decoder Circuit:

click on the image to enlarge

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BCD to Seven Segment Display Decoder Circuit using IC 7447 Reviewed by Author on January 28, 2019 Rating: 5