PCF8574 I2C I/O Expansion Module — 8-Channel GPIO Expander

PCF8574 I2C I/O Expansion Module — 8-Channel GPIO Expander

The PCF8574 I/O expansion module adds 8 additional digital I/O pins to any Arduino via just 2 I2C wires. With 3 address selection pins, up to 8 modules can be connected on a single I2C bus — expanding Arduino to 64 additional GPIO pins. Each pin can be independently configured as input or output. Commonly used to drive LCD displays via I2C.

Key Specifications

• IC: PCF8574 | Channels: 8 GPIO (input/output)
• Interface: I2C | Address range: 0x20–0x27 (3 address pins)
• Max modules per bus: 8 (64 total GPIO)
• Supply voltage: 2.5–6V | Output current: 25mA per pin
• Interrupt output: Yes (INT pin)
• Compliance: RoHS compliant

Why Choose This?

• ✅ 8 GPIO via 2 I2C wires — expand Arduino I/O without using digital pins
• ✅ 8 selectable addresses — stack up to 8 modules for 64 extra GPIO
• ✅ Interrupt output — wake Arduino on input change
• ✅ LCD I2C backpack compatible — standard chip for I2C LCD adapters

Typical Applications

• Arduino GPIO expansion for large projects
• I2C LCD display backpack driver
• Keypad and button matrix scanning
• LED array and relay bank control