Interface - I/O Expanders

Image Part Number Description / PDF Quantity Rfq
PCA9539DWR

PCA9539DWR

Texas Instruments

IC I/O EXPANDER I2C 16B 24SOIC

805

TCA9554ADWT

TCA9554ADWT

Texas Instruments

IC I/O EXPANDER I2C 8BIT 16-SOIC

463

PCA9701PW,118

PCA9701PW,118

NXP Semiconductors

IC SPI GPI 16-BIT 24-TSSOP

4210

PCA8575PW,112

PCA8575PW,112

NXP Semiconductors

PARALLEL I/O PORT

0

PCA9554ADB,118

PCA9554ADB,118

NXP Semiconductors

IC I/O EXPANDER I2C 8B 16SSOP

9846

PCF8574ARGYRG4

PCF8574ARGYRG4

Texas Instruments

IC I/O EXPANDER I2C 8B 20VQFN

0

PCA9557DT

PCA9557DT

Texas Instruments

IC I/O EXPANDER I2C 8B 16SOIC

637

PCA9674APW,118

PCA9674APW,118

NXP Semiconductors

IC I/O EXPANDER I2C 8B 16TSSOP

1568

PCF8574APW

PCF8574APW

Texas Instruments

IC I/O EXPANDER I2C 8B 20TSSOP

301

CAT9554AWI-GT2

CAT9554AWI-GT2

PARALLEL I/O PORT, 8-BIT, 8 I/O

7603

PCA9554PWR

PCA9554PWR

Texas Instruments

IC I/O EXPANDER I2C 8B 16TSSOP

1552

CMS82C55AZ

CMS82C55AZ

Intersil (Renesas Electronics America)

IC I/O EXPANDER 24B 44PLCC

0

PCA9557DGVR

PCA9557DGVR

Texas Instruments

IC I/O EXPANDER I2C 8B 16TVSOP

1455

MCP23018T-E/SS

MCP23018T-E/SS

Roving Networks / Microchip Technology

IC I/O EXPANDER I2C 16B 24SSOP

0

PCA9539PWR

PCA9539PWR

Texas Instruments

IC I/O EXPANDER I2C 16B 24TSSOP

2860

PCF8575RGER

PCF8575RGER

Texas Instruments

IC I/O EXPANDER I2C 16B 24VQFN

1334

PCA9506BS,118

PCA9506BS,118

NXP Semiconductors

IC I/O EXPANDER I2C 40B 56HVQFN

4259

PCF8574TS/3,112

PCF8574TS/3,112

NXP Semiconductors

IC I/O EXPANDER I2C 8B 20SSOP

0

PCA9673BS,118

PCA9673BS,118

NXP Semiconductors

IC I/O EXPANDER I2C 16B 24HVQFN

0

PCAL6408AHKX

PCAL6408AHKX

NXP Semiconductors

IC I/O EXPANDER 8BIT I2C 16XQFN

0

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

TypeFunctional CharacteristicsApplication Examples
I2C I/O Expanders2-wire serial interface, addressable ports, low-speed operationConsumer electronics, sensor hubs
SPI I/O ExpandersHigh-speed 3-4 wire interface, daisy-chain capabilityIndustrial control systems, motor drivers
GPIO ExpandersGeneral-purpose digital I/O with configurable direction/pull-upEmbedded systems, LED matrix controllers
UART I/O ExpandersAsynchronous serial communication expansionLegacy 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

ParameterDescriptionImportance
Channel CountNumber of programmable I/O lines (8-48 channels)Determines peripheral expansion capability
Supply VoltageOperating range (1.65V-5.5V)Compatibility with system power architecture
Communication SpeedUp to 40MHz (SPI), 3.4MHz (I2C)System latency and throughput requirements
Drive StrengthOutput current per pin (4mA-20mA)Peripheral driving capability
Power ConsumptionQuiescent 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

ManufacturerRepresentative ProductKey Features
Texas InstrumentsPCA955516-bit I2C expander with interrupt generation
NXP SemiconductorsPCAL6416A16-port GPIO with programmable pull-up resistors
Microchip TechnologyMCP2301720MHz SPI interface, 16-channel expansion
STMicroelectronicsSTMPE160016-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

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