PCF8574ADW Equivalent & Substitute Parts

Part Overview

The PCF8574ADW is an 8-bit I/O expander with I2C interface operating at 100 kHz, manufactured by Texas Instruments in a 16-SOIC surface mount package. This component is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. The PCF8574ADW provides remote I/O expansion capabilities with push-pull output configuration and power-on reset functionality, suitable for applications requiring additional digital I/O lines via I2C bus communication.

Substiute Parts

PCF8574ADW

Texas InstrumentsIn Stock: 1715PCF8574ADW Datasheet

Current PartRFQ

PCF8574ADWR

Texas InstrumentsIn Stock: 5469PCF8574ADWR Datasheet

MFR RecommendedRFQ

PCF8574AT/3,518

NXP SemiconductorsIn Stock: 17634PCF8574AT/3,518 Datasheet

DirectRFQ

PCA9554D,118

NXP USA Inc.In Stock: 100226PCA9554D,118 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the PCF8574ADW are qualified based on the following critical parameters that determine functional compatibility:

Primary Substitution Criteria:

• Number of I/O: 8 (exact match required)
• Interface: I2C (primary protocol requirement)
• Output Type: Push-Pull (functional output characteristic)
• Interrupt Output: Yes (feature requirement)
• Package / Case: 16-SOIC form factor (mechanical compatibility)
• Mounting Type: Surface Mount (assembly compatibility)
• Operating Temperature Range: -40°C ~ 85°C (environmental specification)
• RoHS Status: ROHS3 Compliant (regulatory requirement)

Secondary Compatibility Parameters:

• Voltage Supply Range: Minimum 2.5V operation required
• Clock Frequency: 100 kHz minimum acceptable

Substitutes are grouped into two categories: direct pin-compatible replacements from the same manufacturer (Texas Instruments PCF8574ADWR) and functionally equivalent alternatives from other manufacturers (NXP PCF8574AT/3,518 and PCA9554D,118) that meet all primary criteria while potentially offering enhanced specifications.

Parameter Comparison

Engineering Selection Recommendations

PCF8574ADWR (Texas Instruments): This is the manufacturer-recommended direct substitute. It maintains identical electrical specifications and package configuration as the PCF8574ADW while offering active product status and improved availability. The transition from tube to cut tape packaging does not affect functional compatibility. This option is preferred for designs requiring minimal qualification effort and maximum pin-level compatibility.

PCF8574AT/3,518 (NXP Semiconductors): This part provides functional equivalence with identical I/O count, interface protocol, and operating parameters. The reduced source current specification (300µA versus 1mA) and elevated moisture sensitivity level (MSL 2) represent minor deviations that do not affect standard I2C bus applications. This option offers higher inventory availability and active product status.

PCA9554D,118 (NXP USA Inc.): This substitute provides enhanced clock frequency capability (400 kHz versus 100 kHz) and SMBus protocol support in addition to I2C compatibility. The increased output source current (10mA versus 1mA) and lower minimum supply voltage (2.3V) represent performance improvements. This option is suitable for applications requiring higher I2C bus speeds or SMBus protocol compatibility, with the understanding that firmware must support the higher clock frequency.

All substitute parts maintain ROHS3 compliance, identical operating temperature range, and push-pull output configuration required for direct functional replacement.

Frequently Asked Questions (FAQ)

Q: Can PCF8574ADWR be used as a direct replacement for PCF8574ADW?

A: Yes. The PCF8574ADWR is the manufacturer-recommended substitute with identical electrical specifications, pin configuration, and 16-SOIC package. The only difference is packaging format (cut tape versus tube), which does not affect circuit functionality.

Q: What are the key differences between PCF8574AT/3,518 and the original PCF8574ADW?

A: The PCF8574AT/3,518 maintains all critical functional parameters including 8 I/O, I2C interface, 100 kHz clock frequency, and identical voltage supply range. Minor differences include reduced source current specification (300µA versus 1mA) and higher moisture sensitivity level (MSL 2 versus MSL 1). These differences do not impact standard I2C applications.

Q: Is PCA9554D,118 compatible with PCF8574ADW applications?

A: The PCA9554D,118 is functionally compatible for applications using standard I2C bus speeds. It provides identical I/O count, interface type, and output configuration. The enhanced 400 kHz clock frequency is backward compatible with 100 kHz bus operation. Applications must verify that firmware does not depend on PCF8574-specific register definitions, as the PCA9554 may have different register layouts.

Q: Are all substitute parts available in the same 16-SOIC package?

A: Yes. All substitute parts use the 16-SOIC (0.295", 7.50mm Width) surface mount package, ensuring mechanical and assembly compatibility with existing PCB designs.

Q: Do substitute parts maintain RoHS3 compliance?

A: Yes. All substitute parts listed are ROHS3 compliant, meeting the same regulatory requirements as the original PCF8574ADW.

Q: What is the impact of different moisture sensitivity levels?

A: PCF8574ADWR and PCA9554D,118 have MSL 1 (unlimited shelf life), while PCF8574AT/3,518 has MSL 2 (1-year shelf life). MSL 2 components require controlled storage conditions and have a defined floor life after moisture exposure. For standard manufacturing environments with proper storage, this difference has minimal practical impact.

Q: Can I use PCA9554D,118 at 100 kHz if my application requires that specific clock frequency?

A: Yes. The PCA9554D,118 supports 100 kHz operation. The 400 kHz maximum frequency is an enhanced capability; the device operates correctly at lower frequencies including 100 kHz.