PCF8574DW

Overview

• Category: Integrated Circuit (IC)
• Use: I/O Expander
• Characteristics:
  • 8-bit remote I/O expander for I2C-bus
  • Low standby current consumption of 10 µA
  • Operating voltage range: 2.5V to 6V
  • Open-drain interrupt output
  • 400 kHz I2C-bus interface
• Package: SO-20
• Essence: PCF8574DW is a versatile I/O expander IC that allows users to increase the number of input/output pins of a microcontroller using the I2C-bus protocol.
• Packaging/Quantity: PCF8574DW is typically sold in reels or tubes, with a quantity of 250 units per reel/tube.

Specifications

• Supply Voltage Range: 2.5V to 6V
• Input/Output Voltage Range: 0V to VDD
• Maximum Output Current: 25mA per pin
• Standby Current: 10µA
• I2C-bus Interface Speed: Up to 400 kHz
• Operating Temperature Range: -40°C to +85°C

Pin Configuration

The PCF8574DW has a total of 20 pins, which are assigned as follows:

1. SDA - Serial Data Input/Output
2. SCL - Serial Clock Input
3. A0 - Address Input Bit 0
4. A1 - Address Input Bit 1
5. A2 - Address Input Bit 2
6. P0 - General Purpose I/O Pin 0
7. P1 - General Purpose I/O Pin 1
8. P2 - General Purpose I/O Pin 2
9. P3 - General Purpose I/O Pin 3
10. P4 - General Purpose I/O Pin 4
11. P5 - General Purpose I/O Pin 5
12. P6 - General Purpose I/O Pin 6
13. P7 - General Purpose I/O Pin 7
14. INT - Interrupt Output 15-20. GND - Ground

Functional Features

• PCF8574DW is an 8-bit remote I/O expander that can be controlled through the I2C-bus interface.
• It provides additional input/output pins for microcontrollers with limited I/O capabilities.
• The device operates at low power, making it suitable for battery-powered applications.
• It features an open-drain interrupt output that can be used to signal events to the microcontroller.
• The I2C-bus interface allows for easy integration into existing systems.

Advantages and Disadvantages

Advantages: - Increases the number of I/O pins available to a microcontroller. - Low standby current consumption helps conserve power. - Simple integration with the I2C-bus protocol. - Open-drain interrupt output for event signaling.

Disadvantages: - Limited to 8-bit I/O expansion. - Requires I2C-bus support from the microcontroller.

Working Principles

PCF8574DW works by communicating with a microcontroller through the I2C-bus protocol. The microcontroller sends commands and data to the IC, which then controls the state of its I/O pins accordingly. The I2C-bus interface allows for bidirectional communication, enabling both input and output operations. The IC can be addressed using three address pins (A0, A1, A2), allowing up to eight devices to be connected on the same bus.

Application Field Plans

PCF8574DW finds applications in various fields, including but not limited to:

1. Home automation systems: Controlling lights, fans, and other appliances remotely.
2. Industrial automation: Expanding I/O capabilities of PLCs (Programmable Logic Controllers).
3. Robotics: Adding additional sensors and actuators to robotic systems.
4. IoT (Internet of Things) devices: Enabling communication between microcontrollers and connected devices.
5. Automotive electronics: Extending the I/O capabilities of automotive control units.

Alternative Models

There are several alternative models available that offer similar functionality to PCF8574DW. Some notable alternatives include:

1. MCP23017 - 16-bit I/O expander with I2C-bus interface.
2. MAX7313 - 16-bit I/O expander with serial interface.
3. PCA9555 - 16-bit I/O expander with I2C-bus/SMBus interface.

These alternative models provide different pin counts, interface options, and additional features, allowing users to choose the most suitable option for their specific requirements.

In conclusion, PCF8574DW is a versatile I/O expander IC that offers an easy way to increase the number of input/output pins of a microcontroller using the I2C-bus protocol