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SN74HCT245N

TISN74HCT245N

Texas Instruments
HCT variant for TTL-compatible input thresholds when interfacing 5V TTL legacy devices.
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Overview

The SN74HCT245N is an 8-bit bus transceiver designed for asynchronous two-way communication between data buses. This device features 3-state outputs and is specifically a HCT variant, providing TTL-compatible input thresholds. It is suitable for interfacing with legacy 5V TTL logic devices.

Why Choose This Part

This transceiver's TTL-compatible inputs (HCT variant) are a key advantage for integrating into systems with existing 5V TTL components, simplifying level translation. Its 3-state outputs allow for efficient bus sharing and reduced power consumption when not active. With a 4.5V to 5.5V supply voltage range, it integrates well into standard 5V digital systems.

Applications

TTL to CMOS Level Shifting
Used to translate 5V TTL logic levels to CMOS-compatible levels within a mixed-voltage system, ensuring proper signal integrity and reliable operation.
Data Bus Isolation
Provides isolation between different sections of a data bus, allowing specific bus segments to be enabled or disabled as needed, preventing contention.
Peripheral Interfacing
Enables microcontrollers or other logic devices to communicate with a wide range of peripherals that may operate at 5V TTL logic levels.
Memory Bus Buffering
Buffers memory data buses, reducing the load on the driving device and improving signal drive capability for larger systems.
General Purpose Logic Buffering
Functions as a general-purpose buffer for digital signals, enhancing fan-out capabilities and isolating sensitive components from bus transients.

Key Specifications

Logic Type Transceiver, Non-Inverting
Output Type 3-State
Mounting Type Surface Mount
Package / Case 20-SOIC (0.209", 5.30mm Width)
Voltage - Supply 4.5V ~ 5.5V
Number of Elements 1
Operating Temperature -40degC ~ 85degC (TA)
Supplier Device Package 20-SO
Current - Output High, Low 6mA, 6mA
Number of Bits per Element 8

Getting Started

To use the SN74HCT245N, connect its A and B ports to the respective data buses. The direction control (DIR) pin determines data flow, while the output enable (OE) pin controls the 3-state outputs. Basic logic gate prototyping on a breadboard with a 5V power supply and standard hookup wire is sufficient for initial testing.

Also Consider

SN74LS245N TITexas Instruments - This is a popular LS family TTL-compatible bus transceiver, offering similar functionality with different electrical characteristics suitable for older designs.
SN74HC245N TITexas Instruments - This is the standard HC variant, which is CMOS input compatible and may be more suitable for purely CMOS-based systems without TTL voltage requirements.
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