Texas Instruments SN74AHC540N

Overview

SN74AHC540N from Texas Instruments is an octal noninverting buffer/driver with 3-state outputs, designed for bus line driving and memory address register buffering in digital systems. It operates from 2 V to 5.5 V, supports ±8 mA output drive at 5 V, features dual active-low output-enable inputs (OE1/OE2), and uses PDIP-20 packaging for through-hole prototyping and industrial control applications.

For engineers reviewing the SN74AHC540N datasheet, SN74AHC540N pinout, SN74AHC540N application, or SN74AHC540N equivalent, key selection criteria include its 3-state bus interface capability, 2–5.5 V supply flexibility, low propagation delay (≤7 ns at 5 V, CL = 15 pF), and compatibility with mixed-voltage logic translation due to 5.5 V-tolerant inputs.

Technical Context

The SN74AHC540N implements eight independent noninverting buffer channels, each controlled by a two-input AND gate with active-low enables (OE1 and OE2). When either OE input is high, all eight outputs enter high-impedance state-enabling bidirectional bus sharing without external direction control.

Its AHC logic family delivers CMOS-level power efficiency with TTL-compatible drive strength. Input voltage tolerance up to 5.5 V allows interfacing with higher-voltage logic while operating at lower VCC (e.g., 3.3 V), supporting down-translation in mixed-supply systems.

Key Specifications

Pinout & Package

SN74AHC540N uses a 20-pin plastic dual in-line package (PDIP) with 0.300-inch body width (25.40 mm × 6.35 mm), optimized for through-hole mounting, manual soldering, and breadboard evaluation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal 3-state buffer applications.

Compared with SN74AHCT540N and 74LVC541APW, SN74AHC540N uniquely balances wide supply range (2–5.5 V), 5.5 V-tolerant inputs, and PDIP-20 through-hole compatibility-making it the preferred choice for prototyping, industrial retrofits, and mixed-voltage bus isolation where layout flexibility and voltage interoperability are essential.

Availability

SN74AHC540N is available at Aetrix Electronics and suitable for industrial control systems, legacy computing interfaces, and embedded sensor hub designs requiring stable component supply and long-term manufacturability.

Supply support for SN74AHC540N 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 global semiconductor leader specializing in analog, embedded processing, and logic solutions, with over 90 years of innovation in industrial, automotive, and communications markets.

The SN74AHC540N belongs to TI's AHC logic family, engineered for low-power, high-speed CMOS performance in mixed-voltage digital systems-particularly targeting bus interface, memory expansion, and level translation applications.

FAQ

What is the maximum output current per channel for SN74AHC540N?

The SN74AHC540N supports ±8 mA output current per channel at VCC = 5 V, as specified in the Electrical Characteristics table under IOL/IOH conditions. This rating ensures reliable drive into standard TTL loads and typical PCB trace capacitances without exceeding thermal limits or degrading signal integrity.

Does SN74AHC540N support 3.3 V operation with 5 V input signals?

Yes, SN74AHC540N accepts input voltages up to 5.5 V regardless of VCC level. When powered from 3.3 V, its inputs remain fully compatible with 5 V logic sources-enabling seamless down-translation without external level shifters or clamping circuitry.

How are the two output-enable pins (OE1 and OE2) used in SN74AHC540N?

In SN74AHC540N, OE1 and OE2 are active-low inputs connected to a two-input AND gate per channel. If either OE1 or OE2 is driven high, all eight outputs enter high-impedance state. This allows flexible bus arbitration-e.g., using OE1 for global disable and OE2 for group-select control in modular systems.

What is the typical propagation delay of SN74AHC540N at 5 V supply?

At VCC = 5 V and CL = 15 pF, SN74AHC540N exhibits typical propagation delays of 3.7 ns (tPLH/tPHL) and 4.5–4.7 ns (tPHZ/tPZH) as documented in Section 5.7. These values ensure timing compliance in 8-bit address/data paths operating below 100 MHz with adequate setup/hold margins.

Is SN74AHC540N RoHS compliant and lead-free?

Yes, SN74AHC540N is RoHS compliant and features NiPdAu (NIPDAU) lead finish, as confirmed in the Package Option Addendum. It meets JEDEC J-STD-020 moisture sensitivity Level-1 requirements and is rated for industrial temperature range (–40°C to +125°C).