IC-Mart Your Trusted Source for Interface – I/O Expanders Chips

(from leading manufacturers)

Mainstream Manufacturers and Representative Models

1. Texas Instruments (TI)

• 8-bit models: TCA9534, TCA9554, PCA9534, PCA9554
• 16-bit models: TCA9535, TCA9555, TCA6416A (with level translation), PCA9535, PCA9555
• 24-bit models: TCA6424A
• Keypad specific: TCA8418 (supports keypad scanning)
• Features: Complete product line covering automotive (Q1) to industrial grades. Excellent documentation support.

2. NXP Semiconductors

• Standard I2C Interface:
  • 8-bit: PCF8574 (a classic), PCA9554, PCA9557, PCAL6408A (with Agile I/O)
  • 16-bit: PCF8575, PCA9555, PCA9535, PCAL6416A
  • 40-bit: PCA9698 (ultra-high pin count)
• SPI Interface: PCAL9722 (22-bit), PCAL9714 (14-bit)
• Features: The new PCAL series features “Agile I/O” (programmable pull-up resistors, latching, and enhanced drive strength).

3. Microchip

• I2C Interface:
  • 8-bit: MCP23008, MCP23009
  • 16-bit: MCP23017 (one of the world’s most famous 16-bit I2C expanders), MCP23018
• SPI Interface:
  • 8-bit: MCP23S08, MCP23S09
  • 16-bit: MCP23S17 (the SPI version of MCP23017)
• Features: Extensive library and open-source support. Ideal for rapid prototyping.

4. Analog Devices / Maxim Integrated (ADI)

• Representative Models:
  • 8-bit: MAX7310, MAX7315, MAX7319
  • 16-bit: MAX7311, MAX7312, MAX7313 (with 16-channel PWM LED control), MAX7318
  • Multi-bit/Specialty: MAX7300 (28-bit I2C), MAX7301 (28-bit SPI)
  • 1-Wire Interface: DS2408 (unique 1-wire 8-bit expansion)
• Features: Superior ESD protection and unique serial interface technologies.

5. Diodes Incorporated

Diodes offers high-value, cost-effective parts compatible with mainstream models.

• Representative Models:
  • 8-bit: PI4IOE5V6408, PI4IOE5V9554
  • 16-bit: PI4IOE5V6416, PI4IOE5V9555
• Features: Often used as drop-in replacements for TI or NXP. Widely used in consumer electronics.

6. onsemi

Primarily serves the computing and automotive markets.

• Representative Models: CAT9532 (16-bit with LED dimming), CAT9554, CAT9555, FXL6408 (low-voltage 8-bit).
• Features: Strong focus on low-voltage environments and integrated LED drivers.

Part Number Replacement Logic (Mouser Search Guide)

When searching on Mouser, follow this logic to find alternatives:

• The Classics: Search 8574 or 8575 (available from NXP/TI).
• Mainstream Industrial: Search 9535 or 9555 (the 16-bit industrial standard).
• Modern/Low Power: Look for TI’s TCA series or NXP’s PCAL series.
• High Speed: Search MCP23S17 (SPI interface).

Core Chinese Manufacturers and Models

Manufacturer	Representative Models	Cross-Reference / Compatible	Core Features
AWINIC	AW9555 / AW9535	TCA9555 / TCA9535	16-bit I2C with interrupt. Used in mobile and industrial.
	AW9523B	PCA9523	16-bit I2C. Supports 64-level dimming for LED driving.
	AW95124	TCA6424A	24-bit ultra-expansion with level translation.
SensyLink	CA9555 / CA9535	TCA9555 / TCA9535	16-bit I2C. Ultra-low standby current (down to 1uA).
	CA9539	TCA9539	16-bit I2C with hardware reset (RESET).
SGMicro	SGM4594	TCA9554	8-bit I2C. High-reliability industrial design.
Semidrive	E3010 (IOE)	–	Automotive-grade. Supports up to 326 GPIOs.
Hotchip	HTR3310 / HTR3306	AW9110 / AW9106	Combined 10-bit/6-bit LED driver and GPIO controller.
WCH	CH367 / CH384	–	Focus on PCIe/USB to multi-GPIO for PC interfaces.

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Interface – I/O Expanders Core Functions: Why are they necessary?

Hardware designers use I/O expanders to solve three main pain points:

1. Pin Exhaustion: Native GPIOs are already used for screens or sensors. The expander adds pins for LEDs or buttons.
2. Wiring Complexity: Reduces cable bulk. Instead of 16 wires for a remote panel, use just 2 wires (I2C) to the expander.
3. Level Mismatch: Acts as a “translator” between a 1.8V MCU and 5V industrial peripherals.

Typical Application Scenarios

1. Industrial Control and Automation

• Control Panels: In heavy machinery (e.g., concrete pumps), expanders collect signals from dozens of switches and drive status LEDs, simplifying the mainboard wiring.
• Sensor Arrays: Monitoring numerous limit or proximity switches on a production line.

2. Consumer Electronics and Smart Home

• Keypad Matrices: Used in laptop keyboards, smart locks, and vacuum robot collision sensors.
• Status Indicators: Driving the rows of blinking LEDs on routers and switches.

3. Computing and Communication

• Server Management: Monitoring power status, fan speeds, or managing hot-swap logic.
• LCD Control: Adding an I2C backpack (often a PCF8574) to 1602 or 12864 LCD modules.

4. Automotive Electronics

• Interior Control: Managing dashboard buttons, window switches, and ambient lighting.

Interface – I/O Expander Classifications

1. I2C / SMBus Interface (Most Common)

Best for low-speed peripherals and saving pins.

• 8-bit: PCF8574 (quasi-bidirectional), TCA9534, PCA9554.
• 16-bit: PCF8575, TCA9555, MCP23017.
• 24-bit and up: TCA6424A (24-bit), PCA9698 (40-bit).

2. SPI Interface (High-Speed Response)

Best for high toggle rates or when I2C resources are limited.

• 8-bit: MCP23S08, 74HCT595 (Shift Register).
• 16-bit: MCP23S17, MAX7317.

3. Level-Shifting Expanders (Cross-Voltage)

Used when the MCU (e.g., 1.8V) and peripherals (e.g., 3.3V/5V) operate at different voltages.

• Features: Dual power rails (VCC_sys and VCC_io).
• Models: TCA9539-Q1, FXL6408.

4. Specialty/Integrated Expanders

• LED Drivers (Constant Current/PWM): TCA62724, PCA9685 (16-channel PWM).
• Keypad Scanners: TCA8418 (supports 8×10 matrix with FIFO).

Summary of Classification and Brands

Dimension	Core Logic	Leading Brands
Interface	System compatibility (I2C for pin saving, SPI for speed)	TI, NXP, Microchip
Bit Count	Scaling capacity (8/16-bit are standard)	TI, NXP
Voltage	Bridging different logic levels (Level translation)	TI, onsemi
Function	Offloading CPU tasks (PWM or Keypad logic)	NXP, ADI, TI