Interface - I/O Expanders

Image Part Number Description / PDF Quantity Rfq
PCAL9555APW,118

PCAL9555APW,118

NXP Semiconductors

IC GPIO EXPANDER 24TSSOP

12120

PCA9538D,118

PCA9538D,118

NXP Semiconductors

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

0

PCA9534BS,118

PCA9534BS,118

NXP Semiconductors

IC I/O EXPANDER I2C 8B 16HVQFN

13009

PCA9555D,112

PCA9555D,112

NXP Semiconductors

IC I/O EXPANDER I2C 16B 24SOIC

2121

PCA6408AHKX

PCA6408AHKX

NXP Semiconductors

IC I/O EXPANDER 8BIT GP 16XQFN

707

PCA9539BS,115

PCA9539BS,115

NXP Semiconductors

IC I/O EXPANDER I2C/SMBU 24HVQFN

1252

PCA9535BS,118

PCA9535BS,118

NXP Semiconductors

IC I/O EXPANDER I2C 16B 24HVQFN

7836

PCA9702PW,118

PCA9702PW,118

NXP Semiconductors

IC SPI GPI 8BIT 18V 16TSSOP

1267

PCA9535CHF,118

PCA9535CHF,118

NXP Semiconductors

IC I/O EXPANDER I2C 16B 24HWQFN

2987

PCA9671PW,112

PCA9671PW,112

NXP Semiconductors

PARALLEL I/O PORT

99

PCA8574PW,118

PCA8574PW,118

NXP Semiconductors

IC I/O EXPANDER I2C 8B 16TSSOP

5363

PCA9698DGG,518

PCA9698DGG,518

NXP Semiconductors

IC I/O EXPANDER I2C 40B 56TSSOP

2162

PCA9557PW,112

PCA9557PW,112

NXP Semiconductors

IC I/O EXPANDER I2C 8B 16TSSOP

593

PCA9535PW,118

PCA9535PW,118

NXP Semiconductors

IC I/O EXPANDER I2C 16B 24TSSOP

3790

PCA9703PW,118

PCA9703PW,118

NXP Semiconductors

IC SHIFT REG SPI GPI 24TSSOP

4731

PCAL9539AHF,128

PCAL9539AHF,128

NXP Semiconductors

PCAL9539AHF - LOW-VOLTAGE 16-BIT

6000

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

PCAL6524EVJ

PCAL6524EVJ

NXP Semiconductors

ULTRA LOW-VOLTAGE TRANSLATING 24

14042

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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