74HC47 (BCD to 7-Segment Decoder/Driver)

General Description
The 74HC47 is a BCD to 7-segment decoder/driver IC designed to convert a 4-bit Binary Coded Decimal (BCD) input into the correct output signals for driving a 7-segment display. It is commonly used in digital clocks, counters, panel meters, and numeric display circuits.

This IC is typically used with common-anode 7-segment displays.

Key Features

• Converts 4-bit BCD input to 7-segment display output

• Designed for common-anode displays

• High-speed CMOS logic

• Low power consumption

• Suitable for digital display and counting applications

• Includes control pins for lamp test, blanking, and ripple blanking

Main Functions

• Accepts BCD inputs: A, B, C, D

• Decodes numbers 0 to 9

• Activates the required segment outputs: a, b, c, d, e, f, g

• Helps reduce wiring complexity in numeric display circuits

Applications

• Digital counters

• Frequency meters

• Calculator displays

• Embedded electronics projects

• Numeric indicator circuits

• Industrial control panels

Important Note

• Best suited for common-anode 7-segment displays

• For proper operation, current-limiting resistors should be used with the display segments

Package Type

• Commonly available in DIP-16

74HC47 – Pin Functions 

🧠 BCD Inputs

• Pin 7 – A: Least Significant Bit (LSB) input

• Pin 1 – B: BCD input

• Pin 2 – C: BCD input

• Pin 6 – D: Most Significant Bit (MSB) input

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   7-Segment Outputs (Active LOW – for Common Anode)

• Pin 13 – a: Segment A output

• Pin 12 – b: Segment B output

• Pin 11 – c: Segment C output

• Pin 10 – d: Segment D output

• Pin 9 – e: Segment E output

• Pin 15 – f: Segment F output

• Pin 14 – g: Segment G output

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  Control Pins

• Pin 3 – LT (Lamp Test): Forces all segments ON when LOW

• Pin 4 – BI (Blanking Input): Turns OFF all segments when LOW

• Pin 5 – RBI (Ripple Blanking Input): Used for leading zero suppression

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Power Pins

• Pin 16 – VCC: +5V Supply

• Pin 8 – GND: Ground