NXP PCF8574AT I/O Expander

The NXP PCF8574AT is a robust, versatile 8-bit I/O (Input/Output) expander chip that provides a simple solution for expanding I/O capabilities using the I²C-bus interface. This device is particularly useful for microcontrollers where the number of GPIO (General Purpose Input/Output) pins is limited, as it allows the user to control eight additional inputs or outputs through just two pins on the microcontroller.

Key Features

• I²C Interface: The PCF8574AT operates as an I²C slave and can be addressed through a 7-bit address, allowing for multiple devices on the same bus.
• 8-bit Remote I/O Ports: Each PCF8574AT provides an additional eight I/O ports, which can be configured as inputs or outputs.
• Interrupt Output: An interrupt output is provided that can be connected to the interrupt input of a microcontroller. This feature ensures that the microcontroller is alerted on any input change without the need for constant polling.
• Low Standby Current: The device is designed to have a very low standby current, making it ideal for power-sensitive applications.
• Open-Drain Outputs: The I/O pins are designed with open-drain outputs, which allows for higher voltage level interfacing and the ability to connect multiple outputs together for wired-AND configurations.

Applications

The PCF8574AT is suitable for a wide range of applications, especially where additional I/O ports are needed. Common applications include:

• Expanding I/O for microcontroller-based systems
• Servers and personal computers
• Industrial control systems
• Robotics and embedded systems
• Home automation systems

Technical Specifications

• Supply Voltage: 2.5V to 6V
• Frequency: Up to 400 kHz on the I²C bus
• Package: Surface-mounted SO16 packaging for compact designs

The NXP PCF8574AT I/O expander is a highly integrated chip that provides a cost-effective way to increase the I/O capabilities of microcontroller-based systems without the need for additional microcontrollers or complex wiring. Its simple interface and easy scalability make it an excellent choice for both simple and complex digital interfacing applications.