Texas Instruments SN74F245DWE4

Overview

SN74F245DWE4 from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between two 8-bit buses. It features direction control (DIR) and output enable (OE) inputs, operates at 4.5–5.5 V, supports 0°C to 70°C ambient temperature, and delivers 128 mA sink current on B-side outputs - enabling direct drive of TTL/CMOS bus loads in industrial control backplanes.

For engineers reviewing the SN74F245DWE4 datasheet, SN74F245DWE4 pinout, SN74F245DWE4 application, or SN74F245DWE4 equivalent, key selection considerations include its SOIC-20 package footprint, 3-state isolation capability, propagation delay ≤7 ns (VCC = 5 V, CL = 50 pF), and compatibility with legacy 5-V TTL systems requiring bidirectional data routing without bus contention.

Technical Context

The SN74F245DWE4 implements a dual-bus transceiver architecture with independent DIR and OE logic controls: DIR selects data flow direction (A→B or B→A), while OE disables all outputs into high-impedance state for bus isolation. Its F-series bipolar TTL process ensures fast switching (tPLH/tPHL ≤7 ns) and robust noise immunity in electrically noisy environments.

It supports asymmetric drive strength - B-side outputs deliver up to 128 mA sink current (IOL), while A-side outputs provide 48 mA - making it suitable for interfacing low-drive peripherals to higher-current bus segments. All I/O pins tolerate –0.5 V to 5.5 V when disabled, supporting hot-swap and mixed-voltage system integration.

Key Specifications

Pinout & Package

SN74F245DWE4 is housed in a 20-pin SOIC (DW) package measuring 13.0 mm × 7.6 mm × 2.65 mm max height, with 1.27 mm lead pitch and gull-wing leads. The package is RoHS-compliant (NIPDAU finish), MSL Level-1, and optimized for automated surface-mount assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LS245N and SN74HC245N, the SN74F245DWE4 provides optimal balance of speed (≤7 ns), drive strength (128 mA), and TTL compatibility - making it the preferred choice for maintaining performance in legacy 5-V industrial bus architectures without redesigning timing or voltage domains.

Availability

SN74F245DWE4 is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy system bus extensions, and programmable logic interposers requiring stable component supply and long-term obsolescence management.

Supply support for SN74F245DWE4 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 for industrial, automotive, and communications markets.

The SN74F245DWE4 belongs to TI's 74F family of fast TTL logic devices, engineered specifically for high-speed, noise-immune digital interconnect in mission-critical industrial control and test equipment.

FAQ

What is the maximum clock frequency supported by SN74F245DWE4 in a synchronous bus application?

The SN74F245DWE4 does not contain an internal clock; it is an asynchronous transceiver. Its usable bus frequency depends on external timing - with typical propagation delay ≤7 ns and setup/hold times <2 ns, it supports reliable operation in 10–20 MHz synchronous bus systems when paired with appropriate controllers. The SN74F245DWE4 must be synchronized externally via DIR and OE control signals aligned to system clock edges.

Can SN74F245DWE4 be used in a 3.3-V system?

No - the SN74F245DWE4 is specified only for 4.5–5.5 V operation and uses bipolar TTL process technology. Applying 3.3 V violates recommended operating conditions and results in undefined logic thresholds, degraded noise margins, and unreliable output drive. For 3.3-V systems, consider CMOS alternatives like SN74LVC245A, not the SN74F245DWE4.

Does SN74F245DWE4 support hot-swap insertion while powered?

The SN74F245DWE4 tolerates –0.5 V to 5.5 V on outputs in the disabled (high-Z) state, and its absolute maximum ratings allow safe exposure to floating or pre-charged bus lines. However, TI does not characterize or guarantee hot-swap behavior - transient currents during insertion may exceed IOL/IOH limits. Use external series resistors or dedicated hot-swap controllers alongside SN74F245DWE4 for robust live-insertion.

What is the function of Pin 1 (DIR) on SN74F245DWE4?

Pin 1 (DIR) is the direction-control input of the SN74F245DWE4. When DIR = Low, data flows from Port B to Port A; when DIR = High, data flows from Port A to Port B. This bidirectional control enables flexible data routing in shared-bus topologies without requiring separate transmit/receive lines. The SN74F245DWE4 relies on DIR state to configure internal transistor paths - no internal latching occurs.

Is SN74F245DWE4 pin-compatible with SN74LS245N?

Yes - SN74F245DWE4 and SN74LS245N share identical 20-pin SOIC (DW/N) footprints, pin assignments, and functional pinout (DIR, OE, A1–A8, B1–B8, GND, VCC). However, due to differing electrical characteristics (e.g., propagation delay, drive strength, input thresholds), direct substitution requires verification of timing margins and load compatibility in the target design before deploying SN74F245DWE4.