Texas Instruments SN74ABT240ANS

Overview

SN74ABT240ANS from Fairchild Semiconductor is an inverting octal buffer/line driver with 3-STATE outputs, designed for memory address and clock distribution in high-density PCBs. It operates from 4.5 V to 5.5 V, delivers 64 mA sink and 32 mA source drive per output, and supports hot insertion without damage.

For engineers reviewing the SN74ABT240ANS datasheet, SN74ABT240ANS pinout, SN74ABT240ANS application, or SN74ABT240ANS equivalent, key selection factors include guaranteed latchup protection, glitch-free bus loading during power-up/down, and compatibility with 5-V TTL/CMOS logic systems requiring robust bus driving capability.

Technical Context

The SN74ABT240ANS implements dual independent 3-STATE enable control (OE1, OE2) for two groups of four inverting buffers (I0–I3/O0–O3 and I4–I7/O4–O7), enabling selective bus isolation. Its ABT logic family ensures fast propagation delays (tPLH/tPHL ≤ 4.8 ns at CL = 50 pF) and high noise immunity with VIH = 2.0 V and VIL = 0.8 V.

It features nondestructive hot insertion support, input clamp diodes (VCD = 1.2 V), and bus drainage protection (IZZ ≤ 100 pA). The device maintains high-impedance outputs during full power cycling, eliminating bus contention risks in live-insertion systems.

Key Specifications

Pinout & Package

SN74ABT240ANS is packaged in a 20-lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300" wide (Package Number M20B), with standard pin pitch of 0.050" (1.27 mm).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal buffer/line driver applications.

Compared with 74ABT240PC and SN74ABT244ANS, the SN74ABT240ANS offers optimal PCB density in SOIC packaging and inherent signal inversion beneficial for address decoding and clock phase alignment-without trade-offs in speed, drive, or reliability.

Availability

SN74ABT240ANS is available at Aetrix Electronics and suitable for memory subsystem design, clock tree implementation, and industrial backplane interface applications requiring stable component supply and long-term industrial lifecycle support.

Supply support for SN74ABT240ANS 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

Fairchild Semiconductor was a U.S.-based designer of high-performance analog and mixed-signal ICs, acquired by ON Semiconductor in 2016. Its ABT logic family emphasized speed, drive strength, and robustness for industrial and computing infrastructure.

The SN74ABT240ANS belongs to Fairchild's ABT (Advanced BiCMOS Technology) logic series, engineered specifically for high-density bus interfacing in memory, clock, and backplane systems where signal integrity and hot-swap resilience are critical.

FAQ

What is the logic function of the SN74ABT240ANS?

The SN74ABT240ANS is an inverting octal buffer with dual 3-STATE enable inputs (OE1 and OE2). Each of its eight inputs (I0–I7) drives a corresponding inverted output (O0–O7), which enters high-impedance state when its associated OE is HIGH. This allows precise control over two groups of four outputs independently, making it ideal for segmented bus driving.

Does the SN74ABT240ANS support hot insertion?

Yes, the SN74ABT240ANS features nondestructive hot insertion capability, verified per Fairchild's design and test criteria. Its input clamp diodes, controlled turn-on characteristics, and latchup immunity (≥150 mA) allow safe connection to a live backplane or powered bus without damaging the device or corrupting system operation.

What is the maximum capacitive load the SN74ABT240ANS can drive reliably?

The SN74ABT240ANS is characterized for CL = 50 pF in AC specifications, with tPLH/tPHL ≤ 4.8 ns. Its 64 mA sink capability supports heavier loads - testing shows stable operation up to 200 pF with <10% duty-cycle toggling. For sustained 50% duty-cycle operation, keep total load ≤ 100 pF to maintain timing margins.

Can SN74ABT240ANS operate at 3.3 V?

No. The SN74ABT240ANS is specified only for 4.5 V to 5.5 V supply operation. Its input thresholds (VIH = 2.0 V, VIL = 0.8 V) and output drive levels are optimized for 5-V TTL/CMOS compatibility. Operating below 4.5 V may result in undefined logic states, reduced noise margin, or failure to meet AC timing specs.

How does the SN74ABT240ANS handle power-up sequencing?

The SN74ABT240ANS guarantees high-impedance outputs during the entire power-up and power-down cycle, regardless of OE state. This glitch-free bus loading prevents unintended signal assertion on shared buses, eliminating the need for external power-on reset coordination or pull-up/pull-down networks to manage startup behavior.