Texas Instruments SN74HCT245PWR

Overview

SN74HCT245PWR 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 (CL = 50 pF), and operates across 4.5 V to 5.5 V supply range. Its direction control (DIR) and active-low output enable (OE) support isolated bus communication in industrial backplane interfaces.

For engineers reviewing the SN74HCT245PWR datasheet, SN74HCT245PWR pinout, SN74HCT245PWR application, or SN74HCT245PWR equivalent, key selection criteria include 3-state isolation capability, TTL-compatible inputs, 8-channel bidirectional buffering, and TSSOP-20 packaging suitable for space-constrained PCB layouts in factory automation and telecom infrastructure.

Technical Context

The SN74HCT245PWR implements a standard '245 logic function with positive-logic DIR control (high = A→B, low = B→A) and active-low OE enabling full 3-state isolation of both A and B ports. Its CMOS HCT process ensures TTL-voltage compatibility while maintaining low static current (≤80 µA).

Propagation delay is balanced across channels and load conditions: 14 ns typical at 5.5 V/CL = 50 pF, increasing to 25 ns at CL = 150 pF. Output drive strength (±6 mA at 5 V) supports direct connection to up to 15 LSTTL loads without external buffering.

Key Specifications

Pinout & Package

TSSOP-20 package (PW), 6.50 mm × 4.40 mm body size, 0.65-mm lead pitch, RoHS-compliant NiPdAu lead finish, MSL 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 SN74HCT245DWR and 74LCX245MTCX, the SN74HCT245PWR offers the smallest PCB footprint among pin-compatible HCT-family transceivers while maintaining full 5-V operation and industrial temperature range - ideal for high-density industrial controllers where space and thermal management are constrained.

Availability

SN74HCT245PWR is available at Aetrix Electronics and suitable for factory automation interfaces, telecom backplane buffers, and multi-function printer engine control requiring stable component supply and long-term industrial lifecycle support.

Supply support for SN74HCT245PWR 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 with over 50 years of innovation in industrial-grade ICs.

The SN74HCT245PWR belongs to TI's 74HCT logic family, engineered for robust 5-V TTL-compatible bus interfacing in harsh industrial and infrastructure environments where reliability and noise immunity are critical.

FAQ

What is the maximum capacitive load the SN74HCT245PWR can drive while maintaining specified timing?

The SN74HCT245PWR is characterized for CL = 50 pF and CL = 150 pF loads. At 5.5 V supply, typical propagation delay increases from 14 ns (CL = 50 pF) to 25 ns (CL = 150 pF). Driving loads beyond 150 pF may exceed timing margins; for heavier loads, verify setup/hold timing in system-level simulation. The SN74HCT245PWR datasheet specifies performance only up to 150 pF.

Can the SN74HCT245PWR operate with a 3.3-V supply?

No. The SN74HCT245PWR requires a minimum 4.5-V supply and is not rated for 3.3-V operation. Its absolute maximum ratings and recommended operating conditions are defined strictly for 4.5 V to 5.5 V. For 3.3-V systems, consider TI's SN74LVC245A or ON Semiconductor's 74LVC245, which are explicitly designed for 3.3-V logic domains.

How does the SN74HCT245PWR handle unused I/O channels?

Unused A or B pins on the SN74HCT245PWR must not float. TI recommends tying them to GND or VCC via 10-kΩ resistors - never connecting A and B sides of the same channel to opposite logic levels. This prevents undefined states, reduces leakage, and avoids increased ICC. The SN74HCT245PWR OE pin disables outputs but does not affect input biasing requirements.

Is the SN74HCT245PWR pin-compatible with older SN74LS245 devices?

No. While functionally similar, the SN74HCT245PWR and SN74LS245 have identical pinouts (TSSOP-20 for PW variant matches LS245 SOIC-20 pin numbering), but their electrical characteristics differ significantly: HCT uses CMOS inputs with µA-level leakage versus LS TTL's mA-level input current, and HCT has higher output drive (±6 mA vs. ±8 mA LS, but different VOH/VOL specs). System-level validation is required before substitution.

What is the thermal performance of the SN74HCT245PWR in its TSSOP-20 package?

The SN74HCT245PWR in TSSOP-20 (PW) has RθJA = 94.9 °C/W (JEDEC JESD51-2 standard), RθJC(bot) = 30.2 °C/W, and ψJB = 45.1 °C/W. Under worst-case 80-µA ICC and 6-mA switching per channel, junction temperature rise remains within limits at ambient ≤85 °C with standard 2-layer PCB copper pour. No heatsink is required for typical industrial use cases.