7448 BCD To 7 Segment Decoder Driver

The 74LS48 / 7448 is a fast TTL logic IC that decodes 4‑bit BCD inputs into segment‑drive outputs suitable for common‑cathode 7‑segment displays. It features built‑in open‑collector outputs with internal pull‑ups, lamp‑test and blanking controls, making it ideal for numeric display tasks in digital clocks, counters, and DIY gadgets.

7448 BCD To 7 Segment Decoder Driver

The 74LS48 (also labeled 7448) is a widely used BCD-to-7‑segment decoder/driver in the TTL logic family. It converts a 4-bit BCD input (0–9) into the appropriate outputs to light segments a–g on a common-cathode LED display. As a solution tailored for numeric display applications, it simplifies wiring and minimizes microcontroller I/O usage.

Connection is straightforward: four inputs (A–D), plus auxiliary inputs for Lamp Test (LT), Blanking Input (BI/RBO), and Ripple Blank Output (RBI). These features allow functions like display reset, dimming, or suppressing leading zeros.

🛠 Technical Details

Feature	Specification
BCD Inputs	A, B, C, D (4-bit binary coded decimal)
Decoder Outputs	7 segments (a–g), open-collector with pull-ups
Supply Voltage (VCC)	4.75 – 5.25 V (standard 5 V TTL logic)
Output Sink Current	6 mA (typical) per segment
Auxiliary Inputs	Lamp Test (LT), Blanking Input (BI/RBO), RBI
Package Type	DIP‑16, SOIC‑16 TTL logic
Operating Temp	0 °C to 70 °C (commercial specification)
Propagation Delay	~10–15 ns typical

Unlike CMOS variants, the 74LS48’s built‑in pull‑ups eliminate external resistors for simple LED driving setups.

💡 Use Cases & Applications

🔢 Digital Counters & Clock Displays
Converts BCD output from counters into readable digits on your display.
🏭 Industrial & Automation Panels
Ideal for numeric feedback on voltage, RPM, or process value readouts using minimal wiring.
📟 Microcontroller-based Projects
Works well with low-pin microcontrollers—just send BCD-coded outputs to the 74LS48 and it handles segment control.
🚀 Educational Logic Training
Pure TTL logic with visible decoding makes it a great teaching tool in electronics labs.
🧠 Multiple Digit Displays via Multiplexing
Can be combined with decoders like 7490 or microcontrollers for efficient multi-digit control.

🛠️ Pair With

🧩 Electronics Components – coupling resistors, wires, and display modules
🧰 Tools & Accessories – soldering kit and testing gear
⚡ Power Supplies – stable 5 V source for TTL applications

🎥 YouTube Tutorial

📺 For practical wiring and demo, search “74LS48 7 segment decoder tutorial” on YouTube—for example, similar to 7447/7448 comparative guides.

⚠️ Precautions & Tips

Always power the 74LS48 with a regulated +5 V TTL supply for correct logic behavior.
Hold LT and BI/RBO high to disable lamp test or blanking. Driving them low will blank or dim displays.
Prevent floating inputs by tying unused address or control pins to valid logic levels.
While internal pull-ups reduce resistor needs, adding series resistors between outputs and display enhances reliability under heavy drive conditions.

🏁 Summary & Call-to-Action

The 74LS48 / 7448 BCD-to-7-segment driver remains a reliable and easy solution for driving numeric displays from BCD signals. Its TTL compatibility, built-in blanking and test logic, and lack of external resistor requirements make it a staple in control panels, counters, and educational kits.

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