Texas Instruments SN74HCT245PW

Overview

SN74HCT245PW from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in 5-V logic systems. It features ±6-mA output drive at 5 V, 14-ns typical propagation delay (VCC = 5.5 V), and TTL-compatible inputs - enabling robust signal integrity in ribbon-cable and backplane interconnects for industrial control and telecom infrastructure.

For engineers reviewing the SN74HCT245PW datasheet, SN74HCT245PW pinout, SN74HCT245PW application, or SN74HCT245PW equivalent, key selection criteria include its 4.5–5.5-V operating range, active-low output enable (OE), direction-control (DIR) logic, and TSSOP-20 package compatibility with high-density PCB layouts.

Technical Context

The SN74HCT245PW implements a standard '245 logic function with dual-bus isolation via 3-state outputs controlled by OE and directional flow governed by DIR. Its CMOS HCT process ensures TTL-voltage compatibility while maintaining low static current (≤80 µA) and balanced propagation delay across all eight channels.

It operates strictly within 4.5–5.5 V, supports up to 15 LSTTL loads per output, and exhibits defined functional modes: DIR = H enables A→B transmission, DIR = L enables B→A transmission, and OE = H forces all outputs into high-impedance state - eliminating bus contention during system reset or power sequencing.

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 6.50 mm × 4.40 mm body, 0.65-mm lead pitch, surface-mount, RoHS-compliant, 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 SN74LVC245APW and 74ACT245SCX, the SN74HCT245PW uniquely balances TTL compatibility, 5-V robustness, sub-100-µA quiescent current, and proven field reliability in industrial wiring harnesses - making it the preferred choice where legacy interface assurance and low standby power are mandatory.

Availability

SN74HCT245PW is available at Aetrix Electronics and suitable for factory automation interfaces, telecom backplane interconnects, and electronic point-of-sale terminals requiring stable component supply across extended production lifecycles.

Supply support for SN74HCT245PW 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 SN74HCT245PW belongs to TI's HCT logic family, engineered specifically for seamless integration between TTL and CMOS systems in noise-prone industrial environments - emphasizing voltage tolerance, bus isolation, and long-term reliability.

FAQ

What is the maximum operating temperature for the SN74HCT245PW?

The SN74HCT245PW is rated for operation from –40 °C to +85 °C. This industrial temperature range ensures reliable performance in factory automation cabinets, telecom equipment enclosures, and outdoor kiosk electronics where ambient temperatures fluctuate significantly. The device's thermal resistance (RθJA = 94.9 °C/W in TSSOP-20) supports this rating under typical PCB copper pour conditions.

Does the SN74HCT245PW support 3.3-V logic inputs?

No, the SN74HCT245PW does not reliably accept 3.3-V logic inputs. Its input thresholds are TTL-compatible (VIH ≥ 2.0 V, VIL ≤ 0.8 V at VCC = 4.5–5.5 V), meaning a 3.3-V high signal may fall below the guaranteed VIH minimum under worst-case VCC and temperature conditions. For 3.3-V systems, TI recommends the SN74LVC245A instead.

Can unused channels of the SN74HCT245PW be left floating?

No, unused A or B port pins on the SN74HCT245PW must not be left floating. Floating inputs cause undefined internal states, increased ICC, and potential oscillation. TI specifies that all unused I/Os be tied to GND or VCC via 10-kΩ resistors - or directly connected to rail if no contention risk exists - to maintain deterministic logic behavior and minimize power consumption.

What is the purpose of the DIR pin on the SN74HCT245PW?

The DIR (direction) pin on the SN74HCT245PW controls real-time data flow direction: when DIR = HIGH, data passes from Port A to Port B; when DIR = LOW, data flows from Port B to Port A. This single-pin control eliminates the need for separate unidirectional drivers and enables dynamic bus reversal in protocols like IEEE-1284 or custom parallel handshaking schemes.

Is the SN74HCT245PW pin-compatible with other '245 devices in TSSOP-20?

Yes, the SN74HCT245PW shares identical pinout and footprint with other TSSOP-20 '245-family devices including SN74LVC245APW and SN74AHCT245PW. However, electrical differences - such as input voltage compatibility, output drive strength, and propagation delay - require verification before substitution in existing designs.