Texas Instruments SN74HC245NSR

Overview

SN74HC245NSR 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 (VCC = 6 V, CL = 50 pF), and supports isolation via OE control-used in PC motherboard I/O expansion and industrial backplane interfaces.

For engineers reviewing the SN74HC245NSR datasheet, SN74HC245NSR pinout, SN74HC245NSR application, or SN74HC245NSR equivalent, key selection criteria include its wide supply range, 3-state bus isolation capability, low ICC (80 µA max), input current ≤1 µA, and compatibility with LSTTL loads (up to 15).

Technical Context

The SN74HC245NSR implements dual-control logic: DIR selects data direction (A→B or B→A), while OE enables/disables all outputs into high-impedance state-enabling bus sharing without contention. Its CMOS design ensures balanced rise/fall times and reduced output ringing, critical for noise-sensitive backplane and mixed-voltage interfacing.

It supports asynchronous operation across –40°C to +85°C, with absolute maximum ratings including 7 V supply voltage and ±35 mA continuous output current. Thermal resistance (RθJA) is 74.1°C/W in NS package, and ESD robustness meets ±3000 V HBM per JEDEC JS-001.

Key Specifications

Pinout & Package

SN74HC245NSR uses a 20-pin SOP (Small Outline Package) with body size 12.60 mm × 5.30 mm, RoHS-compliant NiPdAu lead finish, and moisture sensitivity level 1 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC245NSR, SN74HCT245NSR offers improved noise immunity in 5 V environments but sacrifices universal 2–6 V operation; 74LVC245APW achieves faster switching at lower voltage but cannot interface 3.3 V and 5 V domains directly-making SN74HC245NSR the optimal choice for mixed-supply bus bridging where robustness and flexibility outweigh raw speed.

Availability

SN74HC245NSR is available at Aetrix Electronics and suitable for PC motherboard expansion, industrial backplane interface, and wearable health data hub applications requiring stable component supply across extended production lifecycles.

Supply support for SN74HC245NSR 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The SN74HC245NSR belongs to TI's 74HC logic family-designed specifically for robust, low-power, voltage-flexible digital interfacing in cost-sensitive and thermally constrained applications.

FAQ

What is the maximum operating temperature for the SN74HC245NSR?

The SN74HC245NSR is rated for operation from –40°C to +85°C ambient temperature. This industrial-grade temperature range ensures reliable performance in embedded controllers, network infrastructure equipment, and consumer electronics environments where thermal management is limited. The NS package's RθJA of 74.1°C/W supports this rating under standard PCB layout conditions with adequate copper pour.

Can SN74HC245NSR interface 3.3 V and 5 V buses without level shifters?

Yes, the SN74HC245NSR can safely interface 3.3 V and 5 V buses because its 2 V to 6 V supply range allows operation at either voltage, and its CMOS inputs accept logic-high thresholds as low as 1.5 V (at VCC = 2 V) and 3.15 V (at VCC = 4.5 V). When powered at 5 V, it reliably interprets 3.3 V logic-high signals; when powered at 3.3 V, its outputs swing to ~3.3 V, compatible with 3.3 V receivers. No external level shifters are required.

How does the OE pin function on the SN74HC245NSR?

The OE (output enable) pin on the SN74HC245NSR is an active-low control that places all A- and B-port pins into high-impedance state when asserted (OE = HIGH). When OE = LOW, the transceiver operates normally under DIR control. To ensure defined high-Z state during power-up/power-down, TI recommends tying OE to VCC via a pullup resistor-minimum value determined by driver sink capability, typically 10 kΩ for most microcontroller GPIOs.

What is the recommended bypass capacitor for SN74HC245NSR?

Texas Instruments recommends a 0.1 µF ceramic bypass capacitor placed as close as possible to the VCC pin (pin 20) of the SN74HC245NSR. This capacitor suppresses high-frequency supply noise generated during output switching transitions. For systems with multiple logic devices or noisy environments, paralleling a 1 µF tantalum or ceramic capacitor improves low-frequency decoupling. Ground connection must be short and low-inductance to maximize effectiveness.

Does SN74HC245NSR support hot-swap operation?

The SN74HC245NSR supports controlled hot-swap operation when OE is used to isolate the device before insertion/removal. Its ±20 mA input clamp current and ±35 mA continuous output current rating allow brief overcurrent events during plug-in transients. However, TI does not guarantee full hot-swap compliance without external current-limiting or sequencing circuitry-designers should assert OE high before physical connection and verify bus voltage ramp rates per system-level safety requirements.