PCF8575 16-Bit I2C I/O Expansion Module

PCF8575 16-Bit I2C I/O Expansion Module is a high-performance 16-bit quasi-bidirectional I/O port expander board utilizing the NXP/TI PCF8575 integrated circuit. Communicating over a standard 2-wire I2C interface, it enables microcontrollers with limited GPIO resources like Arduino UNO, ESP8266, and Raspberry Pi to expand a pair of I2C bus pins into 16 fully functional input or output pins with hardware interrupt support.

Key Features:

• 16 Quasi-Bidirectional I/O Pins: Expands microcontroller capabilities with 16 individual GPIO pins organized into two 8-bit ports (P0–P7 and P10–P17).
• Standard 2-Wire I2C Bus: Uses only SDA and SCL communication lines, preserving vital microcontroller pins for other tasks.
• Hardware Open-Drain Interrupt (INT): Active-LOW interrupt pin alerts the host microcontroller whenever input pin states change.
• Configurable I2C Slave Address: 3 onboard address selection solder jumpers (A0, A1, A2) allow chaining up to 8 modules on the same bus (up to 128 GPIOs).
• Low Power Standby: Low standby current consumption under 10 µA, making it ideal for battery-operated portable instruments.
• Wide Supply Margin: Operates reliably across 2.5V to 5.5V DC, ensuring compatibility with 3.3V and 5V microcontroller platforms.

Technical Specifications:

• Operating Supply Voltage: 2.5V to 5.5V DC
• Standby Current: Less than 10 µA
• Expander IC: PCF8575 16-Bit I2C Bus I/O Expander
• I2C Bus Speed: Standard mode (100 kHz) and Fast mode (400 kHz)
• Default I2C Address: 0x20 (configurable from 0x20 to 0x27 via address jumpers)
• I/O Current Drive: High current sink capability (up to 25 mA per pin for direct LED driving); low current source
• Operating Temperature: -40°C to +85°C

Mechanical Specifications:

• Form Factor: Compact dual-row breakout module layout
• PCB Construction: Double-sided FR4 fiberglass board with blue protective mask
• Mounting Holes: 2x 2.5 mm mounting holes for secure enclosure attachment
• Connector Pitch: 2.54mm (0.1 in) standard pin header spacing
• Weight: Approximately 6.0 g

Dimensions:

• Overall Length: 33.0 mm
• Overall Width: 25.0 mm
• Overall Height: 11.0 mm

Pinout and Wiring:

• VCC: Positive DC power supply (+3.3V to +5V DC)
• GND: Ground reference power connection (0V)
• SDA: I2C bidirectional serial data line connected to microcontroller SDA
• SCL: I2C serial clock line connected to microcontroller SCL
• INT: Open-drain active-LOW interrupt output connected to microcontroller external interrupt pin
• P00 to P07 / P10 to P17: 16 individual quasi-bidirectional input/output pins

Datasheet Reference:

• Refer to the NXP / Texas Instruments PCF8575 Remote 16-Bit I2C and SMBus I/O Expander datasheet for bus timing diagrams, address bit truth tables, and quasi-bidirectional I/O circuit architectures.

Commonly Used in:

• Keypad matrix scanners, pushbutton consoles, and indicator LED panels on resource-constrained microcontrollers
• Multi-relay board controllers and industrial PLC digital output modules
• Liquid crystal displays and 7-segment LED display drivers
• Home automation central hubs managing multiple field sensors without consuming GPIO lines

Applications:

• Microcontroller GPIO expansion
• Matrix keypad input scanner
• 16-channel LED indicator driver
• Multi-channel relay switching board
• Industrial automation digital I/O interface

Equivalent Models:

• MCP23017 16-Bit I2C I/O Expander
• PCF8574 8-Bit I2C I/O Expander
• MCP23S17 SPI 16-Bit I/O Expander
• TCA9535 16-Bit Low-Voltage I2C Expander

Package Includes:

• 1 × PCF8575 16-Bit I2C I/O Expansion Module