Toshiba Semiconductor and Storage TC74HC245APF

Overview

TC74HC245APF from Toshiba Electronic Devices & Storage Corporation is an octal 3-state non-inverting bus transceiver in DIP20 package, operating from 2 V to 6 V supply, with 10 ns typical propagation delay and ±6 mA output drive at 4.5 V - used for bidirectional data bus isolation and level translation in industrial control backplanes.

For engineers reviewing the TC74HC245APF datasheet, TC74HC245APF pinout, TC74HC245APF application, or TC74HC245APF equivalent, key selection criteria include direction control (DIR) logic, 3-state enable timing (tPZL/tPLZ), high-noise-immunity input thresholds (28% VCC), and compatibility with LSTTL load driving requirements.

Technical Context

The TC74HC245APF implements dual-bus bidirectional data flow controlled by DIR and G inputs: DIR = L routes A→B; DIR = H routes B→A; G = H forces all outputs into high-impedance state. It uses silicon-gate C2MOS technology to achieve LSTTL-speed performance with CMOS power efficiency.

All eight data channels share identical DC/AC characteristics: balanced tPLH ≈ tPHL propagation delays, 15 LSTTL load drive capability, and input protection against static discharge. Bus pins require external pull-up/down resistors when floating to prevent undefined states.

Key Specifications

Pinout & Package

DIP20 (Dual In-line Package, 0.3-inch width), 20-pin through-hole, 1.30 g typical weight, RoHS-compliant lead finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HC245N and SN74HC245N, the TC74HC245APF uniquely delivers full industrial temperature support, 2 V minimum VCC, and superior noise immunity - making it the optimal choice for ruggedized, mixed-voltage, and long-lifecycle embedded deployments.

Availability

TC74HC245APF is available at Aetrix Electronics and suitable for industrial PLC backplanes, legacy system data bridges, and test equipment bus interfaces requiring stable component supply across extended temperature ranges and multi-decade product lifecycles.

Supply support for TC74HC245APF 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

Toshiba Electronic Devices & Storage Corporation designs high-reliability semiconductor components for industrial, automotive, and infrastructure applications, with over 40 years of analog and logic IC heritage.

The TC74HC245APF belongs to Toshiba's HC-series CMOS logic family, engineered specifically for robust bidirectional bus interfacing in harsh electromagnetic environments and thermally demanding enclosures.

FAQ

What is the maximum clock frequency supported by the TC74HC245APF in a data bus application?

The TC74HC245APF does not operate on a clock signal - it is an asynchronous bus transceiver. Its usable data rate depends on propagation delay and system timing margins. With 10 ns typical tpd and balanced tPLH/tPHL, it reliably supports bus cycles up to 25 MHz in well-designed layouts with proper termination and decoupling.

Can the TC74HC245APF operate at 3.3 V supply while driving standard LSTTL loads?

Yes. The TC74HC245APF operates from 2 V to 6 V and maintains ±6 mA output drive capability at VCC = 4.5 V. At 3.3 V, VOH remains ≥2.5 V (min.) and VOL ≤0.33 V (max.), meeting LSTTL VIH/VIL thresholds. However, drive strength decreases slightly - verify load capacitance and edge rates in actual layout.

Is the TC74HC245APF pin-compatible with the TC74HC640APF?

No. While both are octal 3-state transceivers in DIP20 packages, TC74HC245APF is non-inverting and TC74HC640APF is inverting. Their truth tables and logic behavior differ fundamentally - swapping them without circuit revision will invert all transmitted data bits.

What happens if the DIR input is left floating on the TC74HC245APF?

A floating DIR input risks metastability and unpredictable data direction. The TC74HC245APF has no internal pull-up/down on DIR. External biasing (e.g., 10 kΩ to VCC or GND) is mandatory. Uncontrolled DIR states may cause bus contention, excessive current draw, or corrupted data transfers.

Does the TC74HC245APF require external pull-up resistors on its bus lines?

Yes - when any bus line (A0–A7 or B0–B7) is in high-impedance state (G = H), it must be pulled to a defined logic level using external resistors. Floating CMOS inputs can drift, increase power consumption, and induce oscillation or latch-up. Pull-up/pull-down values typically range from 4.7 kΩ to 10 kΩ depending on noise environment and speed requirements.