Texas Instruments SN74LS47NG4

Overview

SN74LS47NG4 from Texas Instruments is a BCD-to-seven-segment decoder/driver IC designed for direct interface with common-anode LED displays. It accepts 4-bit binary-coded decimal (BCD) input, provides active-low segment outputs (a–g), includes lamp test (LT̅), ripple blanking input (RBI̅), and blanking input/ripple blanking output (BI̅/RBO̅), and operates over 0°C to 70°C with TTL-compatible logic levels.

For engineers reviewing the SN74LS47NG4 datasheet, SN74LS47NG4 pinout, SN74LS47NG4 application, or SN74LS47NG4 equivalent, key selection criteria include its active-low open-collector outputs, built-in leading-zero suppression via RBI̅/BI̅/RBO̅ chaining, compatibility with common-anode LEDs, absence of internal current-limiting resistors, and PDIP-16 packaging with RoHS-compliant NiPdAu lead finish.

Technical Context

The SN74LS47NG4 implements combinational logic decoding of 4-bit BCD inputs (A0–A3) into seven active-low segment drive signals (a–g) optimized for common-anode LED displays. Its internal logic incorporates priority encoding for blanking control: BI̅ forces all outputs high when asserted, while RBI̅ enables leading-zero suppression when cascaded with RBO̅ across multiple devices.

Unlike CMOS or modern LED drivers, the SN74LS47NG4 uses bipolar TTL circuitry with open-collector NPN output transistors-requiring external pull-up resistors-and lacks on-chip current regulation, necessitating external series resistors per segment to limit LED current to safe levels (typically ≤ 40 mA per output).

Key Specifications

Pinout & Package

SN74LS47NG4 is housed in a 16-pin plastic dual in-line package (PDIP) with 0.3-inch body width and 0.1-inch pin pitch. Pin 1 is located at the left end of the top row, identified by a notch or dot marking on the package.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar BCD-to-seven-segment decoder applications.

Compared with SN74LS47N and SN7447AN, the SN74LS47NG4 delivers optimal balance of low power, TTL-compatible speed, and full feature parity - making it the preferred choice for modern retrofits and education platforms requiring reliability and documentation traceability.

Availability

SN74LS47NG4 is available at Aetrix Electronics and suitable for digital panel meters, industrial counter displays, legacy equipment repair, and educational lab training requiring stable component supply and long-term obsolescence management.

Supply support for SN74LS47NG4 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic ICs with global manufacturing and distribution infrastructure.

The SN74LS47NG4 belongs to TI's classic 74LS logic family, developed for reliable, low-power TTL interfacing in industrial controls, instrumentation, and educational systems where robustness and long-term availability are essential.

FAQ

What is the primary function of the SN74LS47NG4?

The SN74LS47NG4 is a BCD-to-seven-segment decoder/driver IC that converts 4-bit binary-coded decimal inputs into active-low outputs for driving common-anode LED displays. It features lamp test (LT̅), blanking (BI̅), and ripple blanking (RBI̅/RBO̅) functions. Its design enables direct LED interface without additional logic, and the SN74LS47NG4 maintains full compatibility with standard 74LS TTL voltage and timing specifications.

Does the SN74LS47NG4 require external current-limiting resistors?

Yes, the SN74LS47NG4 requires external series resistors on each segment output (pins 9–15) because its open-collector outputs sink current but provide no internal current regulation. For typical red LEDs with 2.0 V forward voltage at 10–20 mA, a 220 Ω to 470 Ω resistor per segment is recommended when operating from 5 V. This ensures safe operation within the SN74LS47NG4's 40 mA per-output absolute maximum rating.

Can the SN74LS47NG4 drive common-cathode displays?

No, the SN74LS47NG4 is specifically designed for common-anode LED displays due to its active-low, open-collector outputs that sink current from display anodes. To drive common-cathode displays-which require active-high sourcing-it would need external inverters or a different decoder such as the SN7448. The SN74LS47NG4's internal logic and output structure do not support direct common-cathode interfacing.

How does leading-zero suppression work on the SN74LS47NG4?

Leading-zero suppression on the SN74LS47NG4 is implemented using the RBI̅ (Ripple Blanking Input) and BI̅/RBO̅ (Blanking Input / Ripple Blanking Output) pins. When RBI̅ is low and the decoded digit is zero, RBO̅ goes low to signal adjacent SN74LS47NG4 devices upstream to blank their outputs. This cascading behavior suppresses non-significant leading zeros in multi-digit displays - for example, "0042" appears as " 42" - using only hardware interconnection, no software involvement.

Is the SN74LS47NG4 RoHS compliant and what is its package type?

Yes, the SN74LS47NG4 is RoHS compliant with NiPdAu lead finish and packaged in a 16-pin plastic dual in-line package (PDIP) with 0.3-inch width. Its package drawing code is "N", and it is rated for 0°C to +70°C operation. The "G4" suffix denotes TI's green packaging standard, confirming compliance with environmental directives without exemptions - verified in TI's official package addendum dated July 2026.