Texas Instruments SN74AHC240DWR

Overview

SN74AHC240DWR from Texas Instruments is an octal 3-state buffer/driver IC designed for bus-oriented memory address, clock, and data line driving in industrial and consumer systems. It features dual 4-bit sections with independent output-enable controls, 5.5V-tolerant inputs, 8mA output drive at 5V, and 4.3ns typical propagation delay at 5V/25°C - enabling high-speed signal routing in smartphone baseband, network switch backplanes, and wearable sensor hubs.

For engineers reviewing the SN74AHC240DWR datasheet, SN74AHC240DWR pinout, SN74AHC240DWR application, or SN74AHC240DWR equivalent, key selection criteria include its SOIC-20 package compatibility, 3.3V/5V supply flexibility, ±25mA per-output current capability, and guaranteed operation across –40°C to +85°C ambient temperature - critical for board-level timing integrity and bus contention control.

Technical Context

The SN74AHC240DWR implements two independent 4-bit non-inverting buffer sections (1A→1Y and 2A→2Y), each controlled by a dedicated active-low output-enable input (1OE, 2OE). Its CMOS AHC logic family delivers balanced rise/fall times, rail-to-rail output swing, and low dynamic power consumption - supporting clean signal transmission on shared buses without latching or storage functionality.

Each output transitions between active drive (LOW/HIGH) and high-impedance states under OE control, eliminating bus contention when multiple drivers share a common line. Input overvoltage tolerance up to 5.5V enables level translation from higher-voltage logic domains into 3.3V or 2.5V systems without external clamping.

Key Specifications

Pinout & Package

SN74AHC240DWR uses a 20-pin SOIC (DW) package measuring 12.80mm × 10.3mm (body: 12.8mm × 7.5mm), RoHS-compliant with NiPdAu lead finish and MSL Level-1 reflow rating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHCT240DWR and SN74LVC240ADWR, the SN74AHC240DWR uniquely balances wide supply range (2V–5.5V), 5.5V input tolerance, and industrial temperature support - making it the only option among the three qualified for mixed-voltage, extended-temperature, and legacy-interoperable designs without redesign.

Availability

SN74AHC240DWR is available at Aetrix Electronics and suitable for smartphone baseband interfaces, industrial network switch backplanes, and medical fitness tracker data aggregation requiring stable component supply across long production lifecycles.

Supply support for SN74AHC240DWR 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 connectivity technologies with over 90 years of innovation in high-reliability electronic components.

The SN74AHC240DWR belongs to TI's advanced high-speed CMOS (AHC) logic family, engineered for low-power, high-drive bus interfacing in industrial, automotive, and portable electronics where signal integrity and voltage flexibility are critical.

FAQ

What is the maximum output current per pin for SN74AHC240DWR?

The SN74AHC240DWR supports ±25mA continuous output current per pin at VCC = 5.5V, with absolute maximum ratings specifying ±25mA per output and ±75mA total device current through VCC or GND. This enables direct driving of multiple CMOS loads or terminated transmission lines without external buffering.

Does SN74AHC240DWR support 3.3V-only operation?

Yes, SN74AHC240DWR operates fully across 2V to 5.5V supply range, including 3.3V nominal systems. At VCC = 3.3V, it delivers 4mA output drive, maintains 5.5V input tolerance, and achieves 5.3ns typical propagation delay - meeting timing requirements for most 3.3V FPGA and MCU interfaces.

Can SN74AHC240DWR replace SN74LS240 in existing designs?

SN74AHC240DWR is not a direct drop-in replacement for SN74LS240 due to differences in logic family (CMOS vs bipolar), input thresholds, and output structure. While both are octal 3-state buffers, SN74AHC240DWR requires pull-up resistors on OE pins for power-up high-Z state and lacks LS-style current-sinking outputs - redesign verification is required.

What is the thermal resistance (RθJA) of SN74AHC240DWR in SOIC-20 package?

The SN74AHC240DWR in SOIC-20 (DW) package has a junction-to-ambient thermal resistance (RθJA) of 81.1°C/W, measured per JESD 51-7. This value assumes standard JEDEC 2-layer test board conditions and informs thermal design margins for continuous operation at elevated ambient temperatures.

Is SN74AHC240DWR pin-compatible with other members of the SN74AHC240 family?

Yes, all SN74AHC240 variants - including SN74AHC240N (PDIP), SN74AHC240NSR (SOP), and SN74AHC240PWR (TSSOP) - share identical 20-pin functional pinout and logic behavior. Mechanical dimensions and thermal characteristics differ by package, but PCB layout and firmware remain interchangeable across variants.