Texas Instruments SN74HC245N

Overview

SN74HC245N from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in digital systems. It operates from 2 V to 6 V, delivers ±6 mA output drive at 5 V, exhibits typical propagation delay of 12 ns (CL = 50 pF), and draws ≤80 µA supply current - enabling low-power, noise-resilient bus isolation in PC motherboard I/O expansion.

For engineers reviewing the SN74HC245N datasheet, SN74HC245N pinout, SN74HC245N application, or SN74HC245N equivalent, key selection criteria include direction-control logic behavior, 3-state enable timing (ten/tdis), voltage-level compatibility across mixed-supply domains (e.g., 3.3 V µC ↔ 5 V peripheral), and PDIP-20 package suitability for prototyping and legacy board repair.

Technical Context

The SN74HC245N implements dual-control asynchronous bus transceivers using silicon-gate CMOS technology. Its DIR input selects data flow direction (A→B or B→A), while OE enables/disables all eight channels simultaneously into high-impedance state - eliminating bus contention without external gating logic.

It features slow edge rates to suppress output ringing on unterminated lines, supports up to 15 LSTTL loads per output, and maintains valid logic thresholds across its full 2–6 V supply range - making it suitable for level-shifting and hot-swap-capable backplane interfaces where signal integrity and power efficiency are co-constrained.

Key Specifications

Pinout & Package

SN74HC245N uses a 20-pin Plastic Dual In-line Package (PDIP) with 24.33 mm × 6.35 mm body size, through-hole mounting, and industry-standard 0.3-inch row spacing - optimized for breadboarding, socket-based test fixtures, and legacy PCB rework.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HC245D and MC74HC245N, SN74HC245N offers superior thermal performance in PDIP packaging (57.0°C/W RθJA), proven reliability in industrial control systems, and direct availability in tube format for lab use - making it optimal for design validation and low-volume deployment where mechanical serviceability matters.

Availability

SN74HC245N is available at Aetrix Electronics and suitable for PC motherboard I/O expansion, industrial PLC backplane interfaces, wearable health sensor hubs, and point-of-sale peripheral bridges requiring stable component supply across long-lifecycle embedded programs.

Supply support for SN74HC245N 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 50 years of innovation in logic ICs and industrial-grade interface solutions.

The SN74HC245N belongs to TI's 74HC logic family, engineered for robustness in mixed-voltage digital systems - targeting applications demanding reliable bidirectional bus isolation, low static power, and wide supply tolerance without sacrificing speed.

FAQ

What is the maximum operating temperature for SN74HC245N?

The SN74HC245N is rated for operation from –40°C to +85°C ambient temperature. This industrial-grade range supports deployment in desktop PCs, network infrastructure equipment, and factory automation controllers where thermal management is constrained. The device's thermal resistance (RθJA = 57.0°C/W) ensures safe junction temperatures under typical load conditions within this envelope. Always verify PCB copper area and airflow in final layout.

Does SN74HC245N support 3.3 V-only operation?

Yes, SN74HC245N fully supports 3.3 V operation: VIH is guaranteed ≥2.0 V and VIL ≤0.8 V at VCC = 3.3 V, and output drive remains ≥±4 mA. It interfaces seamlessly with 3.3 V microcontrollers and FPGAs. However, note that propagation delay increases to ~18 ns (typical) at 3.3 V versus 12 ns at 5 V - verify timing margins in high-speed parallel bus designs.

How should OE and DIR be handled during power-up?

To ensure high-impedance state at power-up, tie OE to VCC via a pullup resistor (10 kΩ typical) and DIR to a known logic level (e.g., GND or VCC) using a pullup/pulldown. TI recommends this because SN74HC245N has no internal power-on reset - undefined OE/DIR states could cause bus contention or unintended data latching before firmware initialization completes.

Can SN74HC245N drive LEDs directly?

Yes, SN74HC245N can drive standard 5 V LEDs directly: each output delivers ±6 mA at 5 V, sufficient for indicator LEDs with series resistors ≥680 Ω. For higher-current LEDs (>10 mA), use external drivers - exceeding ±35 mA per output or ±70 mA total VCC/GND current violates absolute maximum ratings and risks latch-up or permanent damage.

Is SN74HC245N pin-compatible with SN74LS245?

No, SN74HC245N is not pin-compatible with SN74LS245. While both are octal transceivers in 20-pin PDIP packages, SN74LS245 uses TTL logic thresholds and draws significantly higher supply current (ICC ≈ 30 mA vs. 80 µA). Direct substitution causes logic-level mismatches and excessive power dissipation - level-shifting or redesign is required for migration from LS to HC families.