Texas Instruments SN74LS47NE4

Overview

SN74LS47NE4 from Texas Instruments is a BCD-to-seven-segment decoder/driver IC designed for direct interface with common-anode LED displays. It features active-low outputs, lamp test (LT̅), ripple blanking input (RBI̅), and blanking input (BI̅/RBO̅), operates at 4.75–5.25 V, supports 0°C to 70°C ambient, and uses a 16-pin PDIP package.

For engineers reviewing the SN74LS47NE4 datasheet, SN74LS47NE4 pinout, SN74LS47NE4 application, or SN74LS47NE4 equivalent, this page delivers verified functional behavior, confirmed TTL-compatible logic thresholds, real-world segment drive capability (up to 40 mA per output), and validated use in discrete numeric display systems requiring direct anode control without external transistors.

Technical Context

The SN74LS47NE4 implements TTL-compatible BCD decoding with internal NAND-AND-OR-Invert logic to generate seven-segment active-low outputs (a–g). Its BI̅/RBO̅ terminal serves dual function: as blanking input (active-low) and ripple blanking output (active-low open-collector), enabling cascaded zero suppression in multi-digit displays.

It includes asynchronous lamp test (LT̅) that forces all segments ON regardless of BCD input, and ripple blanking input (RBI̅) that suppresses leading zeros when driven low - both functions operate independently of clock or enable signals, confirming fully combinational operation with no internal latching or timing dependencies.

Key Specifications

Pinout & Package

SN74LS47NE4 is housed in a 16-pin plastic dual in-line package (PDIP-N), 0.300" wide, with 0.100" lead pitch and RoHS-compliant NiPdAu lead finish. The package is through-hole mountable and rated for manual or wave soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LS47NE4, SN74LS48N provides identical decoding logic but inverted outputs suited for common-cathode LEDs, while 74HC4511PW offers CMOS efficiency and latch capability at the cost of pinout and voltage-domain incompatibility - making SN74LS47NE4 the sole drop-in solution for legacy common-anode TTL display systems.

Availability

SN74LS47NE4 is available at Aetrix Electronics and suitable for industrial panel meters, digital clock displays, test equipment counters, and legacy microprocessor system displays requiring stable component supply and long-term obsolescence mitigation.

Supply support for SN74LS47NE4 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 broad industrial, automotive, and consumer market reach.

The SN74LS47NE4 belongs to TI's legacy 74LS logic family, engineered for robust TTL-compatible BCD decoding in LED display subsystems where reliability, predictable timing, and through-hole manufacturability remain critical.

FAQ

What is the output configuration of the SN74LS47NE4?

The SN74LS47NE4 features active-low, open-collector outputs designed specifically for common-anode seven-segment LED displays. Each output (a–g) sinks up to 40 mA and requires an external current-limiting resistor tied to VCC. This configuration eliminates the need for external NPN transistors in most discrete display applications and ensures direct compatibility with standard 5 V TTL logic levels.

Can the SN74LS47NE4 drive common-cathode displays?

No, the SN74LS47NE4 cannot directly drive common-cathode displays because its outputs are active-low and open-collector - intended to sink current from the anodes of LEDs. To use common-cathode LEDs, you must select SN74LS48N instead, which provides active-high outputs with identical pinout and BCD decoding logic but reversed polarity.

How does ripple blanking work on the SN74LS47NE4?

Ripple blanking on the SN74LS47NE4 uses the RBI̅ (Ripple Blanking Input) and BI̅/RBO̅ (Blanking Input / Ripple Blanking Output) pins to suppress leading zeros in multi-digit displays. When RBI̅ is low and the BCD input is 0, all segment outputs go high (blanked), and RBO̅ goes low to blank the next most-significant digit - enabling hardware-only zero suppression without microcontroller involvement.

What is the purpose of the lamp test (LT̅) pin on the SN74LS47NE4?

The LT̅ (Lamp Test) pin on the SN74LS47NE4 is an asynchronous active-low input that forces all seven segment outputs (a–g) low regardless of BCD input state. This allows full visual verification of LED continuity, wiring integrity, and driver functionality during manufacturing test or field maintenance - a critical diagnostic feature for safety-critical or serviceable display systems.

Is the SN74LS47NE4 RoHS compliant?

Yes, the SN74LS47NE4 is RoHS compliant, with NiPdAu (nickel-palladium-gold) lead finish and exemption status documented in TI's official packaging addendum. It meets EU Directive 2011/65/EU requirements and is suitable for commercial applications operating from 0°C to +70°C, with no lead content exceeding allowable thresholds.