Description

The 7448 BCD to 7-Segment Decoder / Driver is a versatile TTL logic IC designed to convert a 4-bit binary-coded decimal (BCD) input into outputs suitable for driving a 7-segment display. Unlike the 7447, the 7448 features internal pull-up resistors, allowing it to directly interface with common-cathode 7-segment displays without the need for external resistors. This makes the IC ideal for digital counters, clocks, educational kits, and other numerical display applications.

Housed in a 16-pin Dual Inline Package (DIP), the 7448 offers high-speed, reliable operation, and compatibility with other TTL logic ICs. Its internal pull-ups simplify circuit design, reduce component count, and ensure consistent segment illumination, making it a popular choice in both academic and industrial digital electronics projects.

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⚙️ Key Features:

• Function: BCD (Binary-Coded Decimal) to 7-segment decoder/driver

• Logic Family: TTL (Transistor-Transistor Logic)

• Inputs: 4 BCD inputs (A, B, C, D)

• Outputs: 7 outputs (a–g) with internal pull-up resistors

• Active HIGH Outputs: Suitable for common-cathode 7-segment displays

• Standard 16-Pin DIP Package: Easy to use in breadboards and PCB designs

• Operating Voltage: 4.75V to 5.25V typical (TTL standard)

• Low Power Dissipation: Efficient and reliable operation

• High-Speed Operation: Fast propagation delay for real-time display updates

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🧩 Pin Configuration (16-Pin DIP):

The pinout allows straightforward interfacing with BCD inputs and standard 7-segment displays.

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⚡ Electrical Characteristics:

• Supply Voltage (VCC): 5V TTL standard

• Input High Voltage (VIH): ≥ 2V

• Input Low Voltage (VIL): ≤ 0.8V

• Output Current (IOH/IOL): 8 mA typical per segment

• Propagation Delay: ~25 ns typical

• Power Dissipation: ~50 mW

The internal pull-ups allow the IC to drive common-cathode 7-segment displays directly without additional resistors, simplifying the design.

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🧠 How It Works:

The 7448 IC accepts a 4-bit BCD input (0000–1001) and decodes it into 7 outputs (a–g) to illuminate a common-cathode 7-segment display.

• BCD Inputs (A–D): Represent decimal numbers 0–9 in binary

• Segment Outputs (a–g): Control the corresponding display segments

• Active HIGH Outputs: A HIGH signal lights up the segment in a common-cathode display

• Lamp Test (LT): Turns on all segments for testing

• Blanking Input (BI) and Ripple Blanking Input (RBI): Control leading-zero suppression in multiple-digit displays

The internal pull-ups ensure consistent logic levels and prevent floating outputs, improving display stability.

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🛠️ Applications:

• Digital Counters and Timers – Directly display numeric output

• Clocks and Stopwatches – Show hours, minutes, and seconds

• Educational Kits – Teaching BCD-to-7-segment conversion

• Embedded Systems – Provide visual numeric output without extra resistors

• Scoreboards and Digital Displays – Reliable segment illumination

• Test Equipment – Lamp test and blanking features for verification

• Digital Control Systems – Simplify display logic for microcontrollers

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💡 Advantages:

• Internal pull-ups reduce the need for external resistors

• Directly drives common-cathode 7-segment displays

• TTL compatible for easy integration with other digital ICs

• Lamp test and blanking features for flexible control

• Fast and reliable operation with minimal circuit complexity

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📦 Package Includes:

• 1 × 7448 BCD to 7-Segment Decoder / Driver IC (DIP-16) with Internal Pullups

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📘 Conclusion:

The 7448 DIP BCD to 7-Segment Decoder / Driver is a high-performance IC ideal for directly driving common-cathode 7-segment displays. With internal pull-ups, TTL compatibility, lamp test, and blanking features, it provides a simple, reliable, and efficient solution for digital counters, clocks, scoreboards, and educational projects, reducing the need for additional components and simplifying design.