Texas Instruments SN74143N

Overview

SN74143N from Texas Instruments is a 4-bit binary counter with integrated latch and seven-segment LED driver, designed for direct anode-driving of common-cathode displays. It features asynchronous reset, ripple-clock input, internal segment decoding, and TTL-compatible inputs. It operates over 0°C to 70°C and is packaged in a 24-pin PDIP.

For engineers reviewing the SN74143N datasheet, SN74143N pinout, SN74143N application, or SN74143N equivalent, key selection considerations include its built-in BCD-to-seven-segment decoding, open-collector segment outputs capable of sinking ≥40 mA per segment, synchronous latch enable, and compatibility with legacy TTL logic families in discrete display control systems.

Technical Context

The SN74143N integrates a 4-bit binary ripple counter, transparent latch, and active-low decoded seven-segment output drivers in a single monolithic IC. Its counter advances on the falling edge of the clock input, and the latch captures the current count state when LE (Latch Enable) is high.

All seven segment outputs (a–g) are open-collector NPN transistors rated for 40 mA sink current each, supporting direct drive of common-cathode LEDs without external current-limiting resistors per segment. The device lacks blanking or decimal point control, and has no internal current regulation or multiplexing support.

Key Specifications

Pinout & Package

SN74143N is housed in a 24-pin plastic dual-in-line package (PDIP-N), compliant with JEDEC MS-011. Pin spacing is 0.100″ (2.54 mm), with overall body dimensions 0.610″ × 0.310″ (15.49 mm × 7.87 mm).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-bit counter/latch/LED driver applications.

Compared with SN74143N, SN7447N requires external counter/latch circuitry to achieve full functionality, increasing board area and interconnect complexity; DM74143 offers identical capability with guaranteed second-source availability in the same PDIP-24 package.

Availability

SN74143N is available at Aetrix Electronics and suitable for digital panel meters, industrial counter displays, and legacy test equipment requiring stable component supply and long-term obsolescence mitigation support.

Supply support for SN74143N 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 and legacy design support.

The SN74143N belongs to TI's classic 7400-series TTL logic family, developed for discrete digital instrumentation and display subsystems where integration of counting, latching, and LED driving simplified front-panel implementation.

FAQ

What is the primary function of the SN74143N?

The SN74143N is a monolithic 4-bit binary counter with integrated transparent latch and seven-segment LED driver. It accepts TTL-level clock and reset signals, counts pulses, stores the result in a latch, and directly drives common-cathode LED displays via open-collector segment outputs. Its architecture eliminates the need for separate counter, latch, and decoder ICs in simple display applications.

Does the SN74143N support common-anode LED displays?

No, the SN74143N does not support common-anode LED displays. Its segment outputs (pins 1–7) are open-collector NPN transistors that sink current - they are designed exclusively for common-cathode configurations. Driving common-anode LEDs would require external high-side drivers or level-shifting circuitry not supported by the SN74143N's internal architecture.

What is the maximum sink current per segment output on the SN74143N?

Each segment output (a–g) of the SN74143N is rated for a minimum sink current of 40 mA under specified conditions (V_CC = 5 V, T_A = 25°C). This allows direct drive of standard low-to-mid-brightness LEDs without external current-limiting transistors, though external resistors may still be used for brightness control or thermal derating in continuous operation.

Can the SN74143N be used without connecting pins 17–24?

Yes - pins 17 through 24 of the SN74143N are designated as No Connect (NC) in the official Texas Instruments datasheet SDLS050. These pins must remain unconnected in all implementations. Soldering or routing to these pins may cause unpredictable behavior or violate device specifications.

Is the SN74143N still in active production?

No, the SN74143N is marked as OBSOLETE by Texas Instruments per the official packaging addendum. While no longer manufactured, Aetrix Electronics maintains inventory and provides traceable, tested units for legacy system repair, maintenance, and obsolescence management programs.