Interface - I/O Expanders

Part Number	Description / PDF	Quantity
CAT9554YI-GT2 Sanyo Semiconductor/ON Semiconductor	IC I/O EXPANDER I2C 8B 16TSSOP	1775
PCA9654EDTR2G Sanyo Semiconductor/ON Semiconductor	IC I/O EXPANDER 8BIT I2C 16TSSOP	0
PCF8575DW Texas Instruments	IC I/O EXPANDER I2C 16B 24SOIC	54
CY8C9560A-24AXIT Cypress Semiconductor	IC I/O EXPANDER I2C 60B 100LQFP	0
PCA9557DBR Texas Instruments	IC I/O EXPANDER I2C 8B 16SSOP	1229
MAX7301AAX+ Maxim Integrated	IC I/O EXPANDER SPI 28B 36SSOP	283213770
PCA9557PW,118 NXP Semiconductors	IC I/O EXPANDER I2C 8B 16TSSOP	27562
VSC7161XHK Analog Devices, Inc.	10 PORT SAS EXPANDER AT 1.5GBPS	3159
MCP25050-I/P Roving Networks / Microchip Technology	IC I/O EXPANDER CAN 8B 14DIP	72
PCF8574APWR Texas Instruments	IC I/O EXPANDER I2C 8B 20TSSOP	2708
PCF8575DBQR Texas Instruments	IC I/O EXPANDER I2C 16B 24QSOP	1972
TCA9534ADWT Texas Instruments	IC I/O EXPANDER I2C 8B 16SOIC	117
PCA9672D,518 NXP Semiconductors	IC I/O EXPANDER I2C 8B 16SOIC	1000
XRA1200IG16TR-F MaxLinear	IC I/O PORT EXPANDER 8 BIT I2C G	0
MAX7317AEE+T Maxim Integrated	IC I/O EXPANDER SPI 10B 16QSOP	5936
SX1503I091TRT Semtech	IC GPIO EXPANDER I2C 16CH 28-QFN	7218
PCA9555PW,118 NXP Semiconductors	IC I/O EXPANDER I2C 16B 24TSSOP	9797
MAX7318ATG+T Maxim Integrated	IC I/O EXPANDER I2C 16B 24TQFN	0
MAX7319AEE+ Maxim Integrated	IC I/O EXPANDER I2C 8B 16QSOP	9720800
PCA9703PW/Q900,118 NXP Semiconductors	IC GPI 16-BIT SPI 24-TSSOP	188

Interface - I/O Expanders

1. Overview

I/O Expanders are integrated circuits that provide additional input/output ports for microcontrollers, processors, or other digital systems. They enable peripheral expansion through standardized communication protocols (e.g., I2C, SPI) while maintaining signal integrity and system efficiency. These devices play a critical role in modern electronics by simplifying board design, reducing pin count requirements, and enabling scalable system architectures.

2. Main Types & Functional Classification

Type	Functional Characteristics	Application Examples
I2C I/O Expanders	2-wire serial interface, addressable ports, low-speed operation	Consumer electronics, sensor hubs
SPI I/O Expanders	High-speed 3-4 wire interface, daisy-chain capability	Industrial control systems, motor drivers
GPIO Expanders	General-purpose digital I/O with configurable direction/pull-up	Embedded systems, LED matrix controllers
UART I/O Expanders	Asynchronous serial communication expansion	Legacy device integration, communication modules

3. Structure & Composition

Typical I/O Expander ICs consist of: - Communication interface controller (I2C/SPI/UART) - Register arrays for configuration/status storage - Programmable port drivers (CMOS/TTL compatible) - Power management circuitry (low-power modes) - Protective structures (ESD protection, overcurrent) Available in standard packages: TSSOP, QFN, SOIC (8-28 pin configurations)

4. Key Technical Specifications

Parameter	Description	Importance
Channel Count	Number of programmable I/O lines (8-48 channels)	Determines peripheral expansion capability
Supply Voltage	Operating range (1.65V-5.5V)	Compatibility with system power architecture
Communication Speed	Up to 40MHz (SPI), 3.4MHz (I2C)	System latency and throughput requirements
Drive Strength	Output current per pin (4mA-20mA)	Peripheral driving capability
Power Consumption	Quiescent current ( A-nA range)	Battery-powered application viability

5. Application Fields

Consumer Electronics: Smartphones (button matrix expansion), Wearables
Industrial Automation: PLC modules, Sensor networks
Automotive Systems: Body control modules, Infotainment interfaces
Medical Devices: Portable diagnostic equipment, Patient monitoring
Smart Energy: Smart meters, Grid monitoring systems

6. Leading Manufacturers & Products

Manufacturer	Representative Product	Key Features
Texas Instruments	PCA9555	16-bit I2C expander with interrupt generation
NXP Semiconductors	PCAL6416A	16-port GPIO with programmable pull-up resistors
Microchip Technology	MCP23017	20MHz SPI interface, 16-channel expansion
STMicroelectronics	STMPE1600	16-bit GPIO with touch screen controller interface

7. Selection Guidelines

Key considerations: - Required channel count with future expansion margin - Communication protocol compatibility (existing system bus architecture) - Voltage level matching with peripherals and MCU - Package type suitability for board space constraints - Operating temperature range for industrial/environmental applications - Integrated features (interrupt generation, pull-up resistors, PWM support) - Cost vs performance trade-offs for volume production

8. Industry Trends

Current development directions include: - Higher integration with analog/mixed-signal capabilities - Development of ultra-low-power variants (<1 A standby) - Increased channel density in compact packages (e.g., 24-ch in 3x3mm QFN) - Enhanced functional safety features (IEC 61508 compliance) - Support for emerging interface standards (I3C, enhanced SPI modes) - Embedded intelligence with local GPIO state machines