Texas Instruments CD74HCT245E

Overview

CD74HCT245E from Texas Instruments is a high-speed CMOS octal bus transceiver with three-state non-inverting outputs, designed for bidirectional asynchronous data transfer between two 8-bit buses. It features direction control (DIR), output enable (OE), 9 ns typical propagation delay at 5 V/15 pF, ±25 mA output drive per pin, and operates across –55°C to 125°C for industrial and military-grade systems.

For engineers reviewing the CD74HCT245E datasheet, CD74HCT245E pinout, CD74HCT245E application, or CD74HCT245E equivalent, this page delivers verified electrical specs, thermal limits, truth table behavior, real-world bus driving capability, and validated alternatives for system-level bus isolation and level translation in mixed-logic environments.

Technical Context

The CD74HCT245E implements a dual-bus architecture with eight independent bidirectional channels, each controlled jointly by DIR (determining A→B or B→A flow) and OE (enabling/disabling all outputs). Its HCT logic family ensures direct LSTTL input compatibility (VIL ≤ 0.8 V, VIH ≥ 2.0 V) while delivering CMOS-level power efficiency.

It supports true three-state operation with IOZ ≤ ±10 µA over full temperature range, exhibits balanced rise/fall times (12–18 ns at 4.5 V), and maintains stable timing under 50 pF load with defined disable/enable delays (tdis/ten = 30–48 ns). No internal pull-ups or latching-operation is purely combinational and edge-transparent.

Key Specifications

Pinout & Package

CD74HCT245E is supplied in a 20-pin plastic dual in-line package (PDIP-N), with 25.40 mm × 6.35 mm body size and through-hole mounting. Pin 1 is marked by a notch or dot; leads are tin-plated (NIPDAU), RoHS-compliant, and rated for manual or wave soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT245N and 74ACT245PC, CD74HCT245E uniquely combines military-grade temperature range, LSTTL input compatibility, and proven bus-driving robustness-making it the preferred choice for ruggedized, mixed-signal, and legacy-interfaced embedded systems where reliability trumps raw speed.

Availability

CD74HCT245E is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive ECU data bridges, and military avionics routing requiring stable component supply, long-term lifecycle assurance, and guaranteed traceability.

Supply support for CD74HCT245E 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 90 years of innovation in high-reliability components.

The CD74HCT245E belongs to TI's legacy HC/HCT logic portfolio, engineered specifically for robust, low-power, wide-temperature bus interfacing in industrial automation, defense systems, and automotive electronics.

FAQ

What is the maximum clock frequency supported by CD74HCT245E in a synchronous bus application?

The CD74HCT245E is a combinational transceiver-not a clocked device-so it does not have a clock input or specified maximum clock frequency. However, its 26–39 ns propagation delay and 12–18 ns transition time support reliable operation in asynchronous 8-bit bus systems up to ~20 MHz, assuming proper PCB layout, termination, and load capacitance ≤50 pF. For CD74HCT245E, timing margins must be calculated from tpd, tdis, and ten values-not clock period.

Can CD74HCT245E be used to interface 3.3 V microcontrollers with 5 V peripherals?

No-CD74HCT245E is not safe for direct 3.3 V logic input. Its HCT inputs require VIH ≥ 2.0 V (compatible with 3.3 V outputs), but VCC must be 4.5–5.5 V, and absolute maximum input voltage is VCC + 0.5 V. Applying 3.3 V to inputs while VCC = 5 V is acceptable, but driving CD74HCT245E outputs into a 3.3 V system risks overvoltage damage unless clamping or level-shifting is added. For true 3.3 V ↔ 5 V translation, use CD74AVC245 or similar dual-supply transceivers instead of CD74HCT245E.

Does CD74HCT245E include internal ESD protection diodes on its I/O pins?

Yes-CD74HCT245E includes built-in ESD protection diodes on all I/O pins, rated per JEDEC JS-001 Class 2 (≥2 kV HBM). The datasheet specifies absolute maximum input voltage limits of VI < –0.5 V or VI > VCC + 0.5 V, and input diode current IIK is rated at ±20 mA. While this provides baseline handling for assembly-level ESD, TI recommends external series resistors (100–500 Ω) and proper grounding practices for systems exposed to frequent human contact or cable disconnection events involving CD74HCT245E.

How does the direction control (DIR) pin affect power consumption in CD74HCT245E?

DIR pin state has no direct effect on static power (ICC), which remains ≤160 µA regardless of DIR logic level. However, dynamic power increases with toggling activity on either A or B ports-regardless of DIR setting-because both sides contribute to Cpd-based switching losses. When DIR = L and data flows B→A, only B-side inputs and A-side outputs switch; when DIR = H, A-side inputs and B-side outputs switch. So DIR indirectly influences which port drives capacitive loads-but total power depends on net toggle rate across all 16 I/Os, not DIR alone. For CD74HCT245E, minimizing unnecessary bus transitions reduces overall dissipation.

Is CD74HCT245E pin-compatible with CD74HC245E?

Yes-CD74HCT245E and CD74HC245E share identical 20-pin PDIP (N) packaging, pinout, and functional block diagram. Both support DIR/OE control and three-state operation. Key differences are electrical: CD74HC245E operates from 2–6 V and has CMOS-compatible inputs (VIH = 3.15 V @ 4.5 V), while CD74HCT245E is 4.5–5.5 V only with LSTTL-compatible inputs (VIH = 2.0 V). Swapping them requires verifying supply voltage and upstream driver logic levels-mechanical replacement is possible, but electrical compatibility must be confirmed for CD74HCT245E.