74LS47 BCD to Seven Segment Decoder Driver IC

The 74LS47 IC has active low outputs that can directly drive common-anode LEDs or incandescent indicators. It takes a binary-coded decimal as input and converts it to a pattern that can be used to control a seven-segment display that can display digits from 0 to 9. BCD stands for binary coded decimal, which is an encoding in which each digit of a number has its own binary sequence (usually of four bits).

NAND gates, input buffers, and seven AND-OR-INVERT gates make up the SN54/74LS47 Low Power Schottky BCD to 7-Segment Decoder/Drivers. They have active LOW, high sink current outputs that can be used to directly drive indicators. To make BCD data and its complement available to the seven decoding AND-OR-INVERT gates, seven NAND gates and one driver are connected in pairs. Lamp test, blanking input/ripple-blanking output, and ripple-blanking input are provided by the remaining NAND gate and three input buffers. The circuits accept 4-bit binary-coded-decimal (BCD) data and decode it to operate a 7-segment display indicator, depending on the condition of the auxiliary inputs.

The 74LS47 receives four lines of BCD (8421) input data and internally creates complements. And it decodes the data with seven AND/OR gates with open-collector outputs that directly control indicator segments. In the ON (LOW) state, each segment output is guaranteed to sink 24 mA. And with a maximum leakage current of 250 A, it can resist 15V in the OFF (HIGH) state. Blanking, lamp test, and cascadable zero-suppression functions were provided through auxiliary inputs.

A BCD to Seven Segment decoder is a combinational logic circuit that accepts a decimal digit in BCD (input). And generates appropriate outputs for the segments to display the input decimal digit.

Applications

• It is usually used in devices such as a display for calculators, digital watches & displays, etc.