PCA9557PWT I/O Expander Equivalent & Substitute Parts

Part Overview

The PCA9557PWT is an 8-bit I/O expander designed for I2C and SMBus communication at 400 kHz, packaged in a 16-TSSOP surface mount configuration. This part is classified as obsolete, making substitute components necessary for new designs and ongoing production requirements. The functional equivalents listed maintain identical electrical specifications and package dimensions, ensuring direct compatibility in existing circuit implementations.

Substiute Parts

PCA9557PWT

Texas InstrumentsIn Stock: 1648PCA9557PWT Datasheet

Current PartRFQ

PCA9557PWR

Texas InstrumentsIn Stock: 30955PCA9557PWR Datasheet

MFR RecommendedRFQ

PI4IOE5V9557LEX

Diodes IncorporatedIn Stock: 5640PI4IOE5V9557LEX Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the PCA9557PWT is determined by strict equivalence across the following critical parameters:

• I/O Configuration: 8-bit I/O expander architecture
• Communication Protocol: I2C and/or SMBus at 400 kHz
• Electrical Specifications: Supply voltage 2.3V ~ 5.5V, operating temperature -40°C ~ 85°C
• Package Compatibility: 16-TSSOP surface mount package with identical pin pitch and dimensions
• Output Characteristics: Open Drain and Push-Pull output capability with 10mA and 25mA source/sink current ratings
• Regulatory Compliance: ROHS3 compliance and MSL Level 1 rating

Both substitute parts meet these criteria and are functionally interchangeable with the original PCA9557PWT in applications requiring 8-bit I/O expansion over I2C/SMBus interfaces.

Parameter Comparison

Engineering Selection Recommendations

PCA9557PWR is the primary recommended substitute. As an active product from Texas Instruments, it provides full specification alignment with the obsolete PCA9557PWT, including identical I/O configuration, interface protocols, electrical ratings, and package dimensions. The higher inventory availability (30,882 units) supports production continuity and supply chain reliability.

PI4IOE5V9557LEX from Diodes Incorporated serves as a secondary alternative. It maintains core functional equivalence with matching I/O count, I2C protocol support, clock frequency, voltage range, and temperature specifications. The 16-TSSOP package ensures mechanical compatibility. Output type and current specifications are not detailed in available documentation; verification against application-specific requirements is necessary before selection.

Both substitutes carry ROHS3 compliance and MSL Level 1 ratings, meeting regulatory and environmental requirements equivalent to the original part.

Frequently Asked Questions (FAQ)

Q: Can PCA9557PWR be used as a direct replacement for PCA9557PWT?

A: Yes. PCA9557PWR is electrically and mechanically identical to PCA9557PWT across all specified parameters, including I/O count, interface protocols, voltage supply range, operating temperature, output characteristics, and 16-TSSOP package dimensions. The primary difference is product status: PCA9557PWR is active while PCA9557PWT is obsolete.

Q: What are the key differences between PCA9557PWR and PI4IOE5V9557LEX?

A: Both parts share identical I/O configuration (8-bit), I2C protocol support, 400 kHz clock frequency, 2.3V ~ 5.5V supply voltage, -40°C ~ 85°C operating temperature, and 16-TSSOP packaging. PCA9557PWR additionally specifies SMBus compatibility and detailed output type/current ratings. PI4IOE5V9557LEX documentation does not include these specifications.

Q: Are package dimensions identical across all three parts?

A: Yes. All three parts use the 16-TSSOP package with 0.173" width and 4.40mm dimensions, ensuring identical PCB footprints and pin compatibility.

Q: Which substitute should be selected for new designs?

A: PCA9557PWR is recommended for new designs due to active product status, full specification documentation, and higher inventory availability. PI4IOE5V9557LEX may be considered as an alternative if supply constraints occur, provided application requirements do not depend on SMBus protocol or specific output current ratings.

Q: Are both substitutes RoHS compliant?

A: Yes. Both PCA9557PWR and PI4IOE5V9557LEX are ROHS3 compliant with MSL Level 1 ratings, meeting environmental and regulatory requirements equivalent to the original PCA9557PWT.