Interface - I/O Expanders

Image Part Number Description / PDF Quantity Rfq
PCF8575CPW

PCF8575CPW

Texas Instruments

PCF8575C REMOTE 16-BIT I2C AND S

3844

SX1508BIULTRT

SX1508BIULTRT

Semtech

IC EXPANDER 8 CHAN 20QFN

27946

PCAL9539AHF,128

PCAL9539AHF,128

NXP Semiconductors

PCAL9539AHF - LOW-VOLTAGE 16-BIT

6000

PCF8575CDWR

PCF8575CDWR

Texas Instruments

IC I/O EXPANDER I2C 16B 24SOIC

1366

PI4IOE5V9539LEX

PI4IOE5V9539LEX

Zetex Semiconductors (Diodes Inc.)

IC I/O EXPANDER 16B I2C 24TSSOP

0

MCP23S18-E/SO

MCP23S18-E/SO

Roving Networks / Microchip Technology

IC I/O EXPANDER SPI 16B 28SOIC

158

MCP23S08-E/P

MCP23S08-E/P

Roving Networks / Microchip Technology

IC I/O EXPANDER SPI 8B 18DIP

1327

XRA1402IG16TR-F

XRA1402IG16TR-F

MaxLinear

IC I/O PORT EXPANDER 8 BIT SPI G

0

PCA9554DBR

PCA9554DBR

Texas Instruments

IC I/O EXPANDER I2C 8B 16SSOP

1580

PCA9539DB

PCA9539DB

Texas Instruments

IC I/O EXPANDER I2C 16B 24SSOP

348

PCF8575PWG4

PCF8575PWG4

Texas Instruments

PARALLEL I/O PORT, 16-BIT, 16 I/

0

PCA9554APWG4

PCA9554APWG4

Texas Instruments

IC I/O EXPANDER I2C 8B 16TSSOP

0

PCF8574APWRE4

PCF8574APWRE4

Texas Instruments

IC I/O EXPANDER I2C 8B 20TSSOP

0

PCA9536DGKR

PCA9536DGKR

Texas Instruments

IC I/O EXPANDER I2C 4B 8VSSOP

402

PCA9555AHF,128

PCA9555AHF,128

NXP Semiconductors

IC I/O EXPANDER I2C 24QFN

10191

PCA9539APW,118

PCA9539APW,118

NXP Semiconductors

IC GPIO EXPANDER 24TSSOP

2919

PCA9554ATS,112

PCA9554ATS,112

NXP Semiconductors

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

2170

PCA9557RGVR

PCA9557RGVR

Texas Instruments

IC I/O EXPANDER I2C 8B 16QFN

2532

PCF8575CDWG4

PCF8575CDWG4

Texas Instruments

IC I/O EXPANDER I2C 16B 24SOIC

0

TCA9535MRGER

TCA9535MRGER

Texas Instruments

REMOTE 16-BIT I2C AND SMBUS, LOW

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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