Interface - I/O Expanders

Image Part Number Description / PDF Quantity Rfq
PCA9554PWR

PCA9554PWR

Texas Instruments

IC I/O EXPANDER I2C 8B 16TSSOP

1552

PCA9557DGVR

PCA9557DGVR

Texas Instruments

IC I/O EXPANDER I2C 8B 16TVSOP

1455

PCA9539PWR

PCA9539PWR

Texas Instruments

IC I/O EXPANDER I2C 16B 24TSSOP

2860

PCF8575RGER

PCF8575RGER

Texas Instruments

IC I/O EXPANDER I2C 16B 24VQFN

1334

PCA9554DW

PCA9554DW

Texas Instruments

IC I/O EXPANDER I2C 8B 16SOIC

530

TCA9539PWR

TCA9539PWR

Texas Instruments

IC I/O EXPANDER I2C 16B TSSOP

240

PCA9534DB

PCA9534DB

Texas Instruments

IC I/O EXPANDER I2C 8B 16SSOP

901

PCA9555DW

PCA9555DW

Texas Instruments

IC I/O EXPANDER I2C 16B 24SOIC

311

TCA9535RTWR

TCA9535RTWR

Texas Instruments

IC I/O EXPANDER I2C 16B 24WQFN

11362

PCF8574PWR

PCF8574PWR

Texas Instruments

IC I/O EXPANDER I2C 8B 20TSSOP

790

PCA9554PW

PCA9554PW

Texas Instruments

PCA9554 REMOTE 8-BIT I2C AND SMB

77889

PCA9534APW

PCA9534APW

Texas Instruments

IC I/O EXPANDER I2C 8B 16TSSOP

4539990

PCA9555DB

PCA9555DB

Texas Instruments

PCA9555 REMOTE 16-BIT I2C AND SM

9883

PCA9557PW

PCA9557PW

Texas Instruments

IC I/O EXPANDER I2C 8B 16TSSOP

1034

PCF8574APWRG4

PCF8574APWRG4

Texas Instruments

IC I/O EXPANDER I2C 8B 20TSSOP

0

PCF8574DGVR

PCF8574DGVR

Texas Instruments

PCF8574 REMOTE 8-BIT I/O EXPANDE

11932

PCF8575CDWE4

PCF8575CDWE4

Texas Instruments

IC I/O EXPANDER I2C 16B 24SOIC

0

PCF8575DBR

PCF8575DBR

Texas Instruments

IC I/O EXPANDER I2C 16B 24SSOP

2895

PCA9534ADGVR

PCA9534ADGVR

Texas Instruments

PCA9534A REMOTE 8-BIT I2C AND LO

17770

PCA9535DW

PCA9535DW

Texas Instruments

IC I/O EXPANDER I2C 16B 24SOIC

260

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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