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Understanding IC 7447: A Comprehensive Guide to BCD to 7-Segment Converters

更新時間: 2023-12-15 18:31:22


The IC 7447 is engineered to translate Binary-Coded Decimal(BCD) data into a format suitable for 7-segment displays, effectively showing numerical values between 0 and 9. In practice, this semiconductor component ingests BCD information and reformats it into seven segments, visualized as integers from 0 to 9 on a digital display.

This article delves into the ultimate IC 7447 pin configuration, workings, and datasheet guide. Everything you need to know about BCD to 7 segment decoder using IC 7447. Suppose you are an electronics enthusiast or a professional dealing with motherboard maintenance.  In that case, the content herein will equip you with practical knowledge to identify this particular chip.

What is IC 7447?

The IC 7447 belongs to the 74xx series of logic components, commonly found in devices like calculators, digital tally systems, timekeeping gadgets, and other data measurement instruments. This chip is not just a BCD (Binary-Coded Decimal) to 7-segment display decoder but also features a 15V open collector output. It's packaged in a 14-pin dual-in-line configuration for widespread distribution.

Regarding functionality, the 7447 IC transforms a Binary-Coded Decimal input into a display-friendly format, suitable for a 7-segment digital readout showcasing numbers from 0 to 9. The BCD is a unique encoding scheme with a distinct four-bit binary sequence representing each numerical digit.


IC 7447 Pin Diagram

IC 7447 pin diagram.png

The IC 7447 pin configuration diagram is outlined as follows:

  • A0, A1, A2, A3 serve as the BCD (Binary-Coded Decimal) input pins.

  • Lamp Test (LT) is designated for testing the display.

  • RBO refers to the Ripple Blanking Output pin.

  • RBI is the Ripple Blanking Input pin.

  • The letters a through g correspond to the output terminals for the seven-segment display.

  • Initially, these labels help validate inputs exceeding a nine BCD count. The circuit incorporates Ripple Blanking Input and Output (RBI and RBO) for zero suppression and integrates automatic features for leading and trailing edges.

Pin Description

Pin NumberDescription
1BCD B Input
2BCD C Input
3Lamp Test
4RB Output
5RB Input
6BCD D Input
7BCD A Input
97-Segment e Output
7-Segment d Output
117-Segment c Output
127-Segment b Output
137-Segment a Output
147-Segment g Output
157-Segment f Output
16Vcc - Positive Supply

The 'Lamp Test' feature is activated whenever either of the Ripple Blanking pins is set to a high-logic state. Moreover, the 74xx series of circuits includes an overriding Blanking Input (BI) that allows for the modulation of lamp brightness through pulsing or deactivating the outputs.

How does IC 7447 Work?

A driver circuit is a specialized combinational logic mechanism that translates several input pathways into corresponding output lines. In the context of a BCD-to-7-segment decoder like the IC 7447, the conversion involves translating Binary-Coded Decimal (BCD) data into its equivalent decimal representation. The architecture and functionality of this specific chip rely heavily on principles of Boolean algebra and logic gates.

The 7-segment display system incorporates four input conduits and expands to seven output lines. A specialized decoder transforms the BCD information into a format suitable for a 7-segment display. The IC 7447 chip is designed to accept and process BCD inputs corresponding to 7-segment display codes, and it can output numeric and character data. Given that the complement of the BCD data is generated internally, there's no need for additional coding or programming.

BCD to 7 Segment Decoder Using IC 7447

The 74xx47 integrated circuit is engineered to control a 7-segment display and is specifically compatible with common anode 7-segment displays, such as the Kingbright SA03 model. The chip receives a 4-bit binary input labelled as DCBA, where D stands for the 8's place, C represents the 4's, B the 2's, and A the 1's. These 4-bit inputs usually originate from a binary counting mechanism.

The display output makes sense only when the 4-bit binary number DCBA falls within the range of 0000 (which represents the digit 0) to 1001 (or the digit 9). This 4-bit binary representation is commonly known as Binary-Coded Decimal (BCD). If you input a binary number greater than 9 into the chip, the display will yield an anomalous output. You can validate this by interacting with the chip's truth table.

Generally, the input lines referred to as "BI/RBO", "", and "LT" are routinely connected to a 5V power supply.

IC 7447 pinout.png

Basic Setup:

  1. Link Vcc (Pin 16), LT (Pin 3), BI/RBO (Pin 4), and RBI(Pin 5) to a 5V power source.

  2. Attach Gnd (Pin 8) to a 0V ground line.

  3. Wire the DCBA inputs (Pins 1, 2, 6, and 7) to the corresponding DCBA outputs from your counter.

  4. Finally, make connections from (Pins 9 through 15) to the abcdefg segments on your common anode 7-segment display.

Advanced Operations:

  • The symbol signifies the 'Lamp Test' function. When this pin is set to a low voltage, all segments of the 7-segment display illuminate,

    independent of the DCBA inputs. To explore this, refer to the truth table below.

7-seg display are lit regardless of DCBA.png

  • The symbol represents the 'Blanking Input'. If this pin is low, the 7-segment display will turn off all segments, irrespective of the DCBA values.

    To see this in action, consult the truth table below.

7seg display are off regardless of DCBA.png

  • The term stands for 'Ripple Blanking Input'. The display remains unlit when this pin is low and DCBA reads 0000. For any other DCBA values,

    the numerical display remains visible. This feature is useful for eliminating leading zeros in numbers, such as displaying '89' instead of '089'.

    When using multiple displays, connect the (Ripple Blanking Output) from the most significant 74xx47 to the input of the subsequent 74xx47

    unit. Connect the pin of the least significant 74xx47 to a 5V source unless you prefer the display to be blank when showing the number zero.

Features and Specifications

The 74xx series of integrated circuits is a prevalent logic family that incorporates logic gates, flip-flops, and counters. In this context, let's delve into the specifications and specific features of the 7447 IC:


  • Features an expansive voltage range for flexibility

  • Operates under diverse conditions

  • Built-in pull-up resistors negate the need for external ones

  • Designed with four input lines and seven output lines

  • Includes input clamp diodes, eliminating the requirement for high-speed termination

  • Equipped with open-collector output

Product Information:

  • Single 7447 IC included in each package

  • IC is labelled with the number 7447

  • Functions as a BCD (Binary-Coded Decimal) to 7-segment converter, capable of displaying numbers 0 through 9

  • Runs on a 5V power supply, with a minimum requirement of 4.75V and a maximum of 5.25V

  • Features 14 to 16 pins, housed in a dual-in-line package (DIP)

Note: Comprehensive technical details can be available in the 7447 datasheet provided at the end of this page.

IC 7447 Datasheet

Download IC 7447 Datasheet PDF.

Here are some key pieces of information from the 7447 IC datasheet:

  • Function table

  • Logic diagram

  • Schematics of inputs and outputs

  • Absolute maximum ratings over the operating free-air temperature range

  • Recommended operating conditions

  • Electrical characteristics

  • Switching characteristics

  • Packaging information

  • Tape and reel information


The IC 7447 is a dependable and effective mechanism for transforming Binary Coded Decimal (BCD) information into 7-segment displays. With a flexible array of capabilities, it has garnered favour among experts and hobbyists. This integrated circuit plays a pivotal role in connecting the realm of binary code to forms that are easily interpretable by people. Its multifunctionality, enhanced attributes, and strong operational capabilities make it crucial in contemporary digital electronics. A thorough understanding of its workings, capabilities, and use cases offers a rich perspective on digital electronics.

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  • Is 7447 an active-low so?
  • As per the datasheet for the 7447, both the 7446A and 7447A integrated circuits come with active-low outputs specifically engineered for directly powering common-anode LEDs or incandescent indicators. Each circuit in this series has comprehensive ripple-blanking input/output functionalities and a feature for testing the lamp.

  • What is the input of 7447?
  • The 74xx47 integrated circuit accepts a binary input coded as DCBA, with D representing the 8s place, C the 4s, B the 2s, and A the 1s. Usually, these DCBA inputs are sourced from a binary counter. The display output makes logical sense only when the binary number falls within the range of DCBA=0000 (which is 0) to DCBA=1001 (which translates to 9). This specific format is known as Binary Coded Decimal, or BCD, in abbreviated form.

  • What does a 7-segment decoder do?
  • A BCD to 7-segment display decoder is a specialized converter that transforms binary-coded decimals into a readily understandable format when displayed on a 7-segment screen.

  • What is the alternative to 7447 IC?
  • 4511.

  • What is the difference between 7447 and 7448?
  • The 7448 is engineered for controlling common cathode configurations, whereas the 7447 is tailored to manage common anode setups.

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