74HC245 Octal Bus Transceiver, 3-State, 20-Pin SO-20

74HC245 Octal Bus Transceiver, 3-State, 20-Pin SO-20

The 74HC245 is an octal bidirectional bus transceiver with three-state outputs, designed for communication between two 8-bit digital buses. It contains eight data channels and uses a DIR input to select the direction of data transfer and an active-low OE input to enable or place the bus outputs into a high-impedance state. This makes it useful for controlling access to shared data buses and preventing bus conflicts.

The device uses CMOS logic technology and supports a wide supply-voltage range from 2.0 V to 6.0 V. The 74HC245 provides non-inverting outputs, low power dissipation, and high noise immunity. The specified SO-20 version is housed in a 20-lead small-outline package and is suitable for compact PCB designs.

Features

• 8-bit bidirectional bus interface.
• Three-state outputs.
• Non-inverting data transfer.
• Separate direction control.
• Active-low output enable.
• High-impedance state for bus isolation.
• CMOS logic technology.
• Low power dissipation.
• High noise immunity.
• Input clamp diodes.
• Suitable for shared-bus systems.
• Compact SO-20 package.

74HC245 Pin Configuration

Specifications

Where to use a 74HC245 IC

The 74HC245 is an 8-bit transceiver IC with 3-state output. Meaning it has two set of pins (A0-A7 and B0-B7), in which each set has 8 pins. Out of these two sets one set can be used as input and the other set can be used as output. Since the IC is a transceiver IC, Data can flow from input bus to output bus and also from output bus to input bus, by simply toggling the Direction pin (DIR) pin as required. It also has a decent output current of 35mA and hence can be used to drive nominal loads.

So if you are looking for an IC to act as a buffer or as a transceiver for your address or data bus. Or if you are looking for an IC to act as a 8-bit logic level converter then 74HC245 IC might be the right choice for you. It is also possible to use this IC for establishing communication protocol buses (SPI, IIC, etc.) between two different MCU/MPU with different operating voltages since the IC has high speed buffer. The 3 State at which 74HC245 IC can operate is shown in the table, the pins OE and DIR can be used as follows to set the state.

How to use the 74HC245 IC

74HC245 IC has a vast application; however for simplicity let us consider we are using the IC to act as logic level converter. Many hardware like Raspberry Pi, MSP430 operates with a voltage of 3.3V, but other sensors or IC’s like Ultrasonic sensor, TFT LCD displays etc operate in 5V. So in these cases we have to shift one set of operating voltage (3.3V) to another set (5V). In these cases we employ a logic level converter; the simplest logic level converter is a potential divider. But it is not efficient for high speed operation or for bi-directional communication buses. Hence in those cases a bi-directional transceiver IC like 74HC245 seems to be an ideal choice.

Applications

• Address bus buffers.
• Data bus transceivers.
• Logic level converters.
• Driver IC for communication protocols.

Packages Included:

• 1 × 74HC245 Octal Bus Transceiver, 3-State, 20-Pin SO-20.

74HC245 Datasheet