Texas Instruments SN7445N

Overview

SN7445N from Texas Instruments is a 16-pin BCD-to-decimal decoder/driver IC designed for direct interface with common-anode 7-segment displays and lamp drivers. It features active-low outputs, TTL-compatible inputs, 15 mA sink current per output, and operates over 0°C to 70°C. Used in digital instrumentation, panel meters, and industrial display systems.

For engineers reviewing the SN7445N datasheet, SN7445N pinout, SN7445N application, or SN7445N equivalent, key selection considerations include its active-low open-collector outputs, BCD input decoding logic, TTL-level compatibility, thermal operating range, and PDIP-16 packaging for through-hole prototyping and legacy board designs.

Technical Context

The SN7445N implements a 4-bit binary-coded decimal (BCD) to 10-line decimal decoder with active-low outputs. Its internal logic decodes inputs A–D (LSB to MSB) into ten mutually exclusive low-active outputs Y0–Y9, with no internal pull-ups - requiring external pull-up resistors for common-anode display interfacing.

It uses standard bipolar TTL circuitry with Schottky-clamped transistors for improved switching speed and noise immunity. Input thresholds align with standard TTL voltage levels (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V), and output saturation voltage is specified at I_OL = 15 mA.

Key Specifications

Pinout & Package

SN7445N is housed in a 16-pin plastic dual in-line package (PDIP-N), 0.3-inch body width, with through-hole mounting and standard 0.1-inch pin pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LS45N and 74HC4511PW, the SN7445N offers superior drive strength and direct TTL compatibility in a legacy-friendly through-hole package - making it optimal for maintaining or repairing existing industrial display hardware without board revision.

Availability

SN7445N is available at Aetrix Electronics and suitable for digital instrumentation, industrial control displays, and test equipment readouts requiring stable component supply and long-term obsolescence resilience.

Supply support for SN7445N 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 and embedded processing technologies with broad industrial, automotive, and consumer product portfolios.

The SN7445N belongs to TI's classic 7400-series TTL logic family, engineered specifically for reliable BCD decoding and direct LED/lamp driving in fixed-function digital display subsystems.

FAQ

What is the primary function of the SN7445N?

The SN7445N is a BCD-to-decimal decoder with active-low open-collector outputs. It converts 4-bit binary-coded decimal inputs (A–D) into ten decoded decimal outputs (Y0–Y9), enabling direct drive of common-anode LED displays or lamp arrays. Its design centers on simplicity, reliability, and TTL compatibility in fixed-display applications.

Does the SN7445N require external pull-up resistors?

Yes, the SN7445N requires external pull-up resistors on all ten outputs (Y0–Y9) because they are open-collector. Without pull-ups, outputs cannot achieve a defined high state. Typical values range from 1.0 kΩ to 4.7 kΩ depending on display brightness and supply voltage, and each resistor connects between V_CC and its respective output pin.

What is the maximum output sink current for the SN7445N?

The SN7445N supports up to 15 mA sink current per output (Y0–Y9) at V_OL ≤ 0.5 V, with V_CC = 5 V and T_A = 25°C. This allows direct driving of standard LEDs or incandescent lamps without additional transistor buffers, provided total package power dissipation remains within limits.

Is the SN7445N pin-compatible with other 74xx45 variants?

Yes, the SN7445N shares identical pinout and logic functionality with SN5445J (military-grade) and SN7445NE4 (same commercial spec, alternate marking). All use the same 16-pin PDIP package and decode BCD inputs identically - enabling direct substitution in through-hole designs where temperature range permits.

Can the SN7445N decode hexadecimal (0–F) inputs?

No, the SN7445N only decodes valid BCD inputs (0000–1001, i.e., decimal 0–9). Inputs 1010 through 1111 (decimal 10–15) are invalid BCD codes; the device holds all outputs high in those cases, preventing unintended activation of display segments or lamps.