Texas Instruments SN74AHC245DW

Overview

SN74AHC245DW from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between two 8-bit buses. It operates across 2V–5.5V V_CC, supports direction control (DIR) and output enable (OE), and delivers 8 mA drive strength at 5 V - enabling robust level translation in mixed-voltage systems such as 5 V ↔ 3.3 V microcontroller interfaces.

For engineers reviewing the SN74AHC245DW datasheet, SN74AHC245DW pinout, SN74AHC245DW application, or SN74AHC245DW equivalent, key selection considerations include its SOIC-20 package thermal resistance (R_θJA = 96.2°C/W), 3.3 V/5 V switching timing (t_PLH/t_PHL ≤ 6.5 ns at 5 V), overvoltage-tolerant inputs (up to 5.5 V), and isolation capability during power-up via OE pull-up.

Technical Context

The SN74AHC245DW implements a dual-bus transceiver architecture with independent DIR and OE controls, allowing real-time reversal of data flow direction without bus contention. Its CMOS AHC logic family ensures low static current (I_CC ≤ 40 µA), rail-to-rail output swing, and input compatibility across 2V–5.5V supply ranges.

Each of the eight bidirectional channels features symmetrical propagation delay (t_PLH ≈ t_PHL) and matched enable/disable timing (t_PZH/t_PHZ ≤ 10 ns at 5 V), supporting clean signal handoff in high-speed digital backplanes and memory expansion interfaces.

Key Specifications

Pinout & Package

SN74AHC245DW uses a 20-pin SOIC (DW) package measuring 12.80 mm × 10.3 mm (body: 12.80 mm × 7.50 mm), with standard 0.65 mm lead pitch and gull-wing leads suitable for reflow soldering.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal bus transceiver applications.

Compared with SN74LVC245A and 74AHCT245, the SN74AHC245DW uniquely balances 5.5 V input tolerance, 2 V minimum supply, and industrial temperature range - making it optimal for voltage-flexible embedded designs where reliability across mixed-signal domains is essential.

Availability

SN74AHC245DW is available at Aetrix Electronics and suitable for server memory expansion, industrial PLC backplane interfaces, and wearable health sensor hubs requiring stable component supply across extended temperature and mixed-voltage conditions.

Supply support for SN74AHC245DW 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 decades of experience in high-reliability logic and interface solutions.

The SN74AHC245DW belongs to TI's AHC logic family, engineered for low-power, high-speed bidirectional bus interfacing in industrial, computing, and communications equipment where voltage translation and noise immunity are critical.

FAQ

What is the maximum recommended operating voltage for SN74AHC245DW?

The absolute maximum V_CC rating for SN74AHC245DW is 7 V, but the recommended operating range is 2 V to 5.5 V per TI's SCLS230N datasheet. Operating above 5.5 V risks exceeding electrical specifications and may cause premature device failure. For sustained reliability in production systems, SN74AHC245DW should be used within the 2–5.5 V window, with 5 V being the nominal target for full drive strength and timing performance.

Can SN74AHC245DW safely interface a 5 V microcontroller with a 3.3 V FPGA?

Yes - SN74AHC245DW supports this exact use case. Its inputs tolerate up to 5.5 V regardless of V_CC, so 5 V logic levels from the microcontroller are accepted safely when SN74AHC245DW is powered at 3.3 V. Outputs swing rail-to-rail, delivering valid 3.3 V logic levels to the FPGA. This makes SN74AHC245DW ideal for bidirectional 5 V ↔ 3.3 V translation without external components.

How should the OE pin be handled during power-up to prevent bus contention?

To ensure high-impedance state at power-up, OE must be held HIGH until V_CC stabilizes. TI recommends tying OE to V_CC via a pull-up resistor; the minimum value depends on the driver's sink capability but is typically 10 kΩ. This guarantees SN74AHC245DW remains disabled during power sequencing, eliminating risk of back-driving or contention on either A or B bus - a critical requirement verified in SN74AHC245DW application notes.

What is the thermal resistance (R_θJA) of SN74AHC245DW in its SOIC-20 package?

The junction-to-ambient thermal resistance R_θJA for SN74AHC245DW in the DW (SOIC-20) package is 96.2°C/W, as specified in Section 5.4 of the TI SCLS230N datasheet. This value assumes standard JEDEC 2-layer board conditions. For higher-power applications, designers should verify board layout (copper area, vias) and ambient temperature to ensure junction temperature stays below 125°C under worst-case load.

Does SN74AHC245DW support hot-swapping or live insertion?

SN74AHC245DW is not explicitly rated for hot-swap operation. While its 3-state outputs and overvoltage-tolerant inputs improve robustness, TI does not guarantee glitch-free behavior during live insertion due to potential supply sequencing issues and undefined OE/DIR states. For true hot-swap applications, dedicated hot-swap controllers or buffers with built-in power sequencing logic are recommended instead of relying solely on SN74AHC245DW.