PCF8574PW Equivalent & Substitute Parts

Part Overview

The PCF8574PW is an 8-bit I/O expander with I2C interface operating at 100 kHz, manufactured by Texas Instruments in a 20-TSSOP surface mount package. This part is classified as obsolete, making substitute components necessary for new designs and ongoing production requirements. The PCF8574PW provides remote I/O expansion capabilities with push-pull output configuration and power-on reset functionality, suitable for applications requiring I2C-based digital I/O control in the 2.5V to 6V supply range.

Key Parameters

Parameter	Value
Number of I/O	8
Interface	I2C
Clock Frequency	100 kHz
Voltage Supply Range	2.5V ~ 6V
Operating Temperature	-40°C ~ 85°C
Output Type	Push-Pull
Interrupt Output	Yes
Features	POR (Power-On Reset)
Mounting Type	Surface Mount
Package	20-TSSOP
RoHS Status	ROHS3 Compliant
MSL Rating	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the PCF8574PW are qualified based on strict electrical and mechanical compatibility within the following parameters:

Critical Matching Parameters:

Number of I/O: 8 channels
Interface Protocol: I2C at 100 kHz
Supply Voltage Range: 2.5V ~ 6V
Operating Temperature Range: -40°C ~ 85°C
Output Configuration: Push-Pull with interrupt capability
Power-On Reset Feature: Required
RoHS3 Compliance: Required
MSL Rating: 1 (Unlimited)

Acceptable Variations:

Manufacturer: Different manufacturers producing equivalent designs
Packaging Format: Tube, Cut Tape, or Digi-Reel formats
Package Designation: 20-TSSOP or 20-LSSOP (mechanically compatible 20-pin shrink small outline packages)
Current Output Specifications: Source/sink current ratings within or exceeding the original specification

Parameter Comparison

Parameter	PCF8574PW (Main)	PCF8574PWR (Substitute)	PCF8574TS/3,118 (Substitute)
Manufacturer	Texas Instruments	Texas Instruments	NXP USA Inc.
Number of I/O	8	8	8
Interface	I2C	I2C	I2C
Clock Frequency	100 kHz	100 kHz	100 kHz
Voltage Supply	2.5V ~ 6V	2.5V ~ 6V	2.5V ~ 6V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Output Type	Push-Pull	Push-Pull	Push-Pull
Interrupt Output	Yes	Yes	Yes
Features	POR	POR	POR
Current - Output Source/Sink	1mA, 25mA	1mA, 25mA	300µA, 25mA
Mounting Type	Surface Mount	Surface Mount	Surface Mount
Package / Case	20-TSSOP	20-TSSOP	20-LSSOP
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
Product Status	Obsolete	Active	Active

Engineering Selection Recommendations

PCF8574PWR (Texas Instruments): This part is the manufacturer-recommended substitute, maintaining identical electrical specifications and package designation (20-TSSOP) to the PCF8574PW. The PCF8574PWR carries active product status with ROHS3 compliance and unlimited MSL rating. This substitute is preferred for direct replacement in existing designs without layout modifications.

PCF8574TS/3,118 (NXP USA Inc.): This part provides functional equivalence with all critical I2C interface parameters, supply voltage range, and operating temperature specifications matching the original. The package designation differs (20-LSSOP versus 20-TSSOP), representing a mechanically compatible shrink small outline variant with identical pin pitch and footprint compatibility. The source current specification is reduced to 300µA compared to the original 1mA, which may require evaluation in applications with specific output drive requirements. This substitute carries active product status with ROHS3 compliance and unlimited MSL rating.

Frequently Asked Questions (FAQ)

Q: Can PCF8574PWR be used as a direct replacement for PCF8574PW?

A: Yes. The PCF8574PWR maintains identical electrical specifications, package type (20-TSSOP), and all functional parameters including I2C interface, I/O count, supply voltage range, and operating temperature. No design modifications are required.

Q: What is the difference between 20-TSSOP and 20-LSSOP packages?

A: Both are 20-pin shrink small outline packages with identical pin pitch (0.65mm) and footprint dimensions (0.173" width, 4.40mm). The primary distinction is the package shrink designation; both are mechanically and electrically compatible for PCB assembly purposes.

Q: Is the PCF8574TS/3,118 suitable for applications requiring 1mA source current?

A: The PCF8574TS/3,118 specifies 300µA source current compared to the original 1mA specification. Applications requiring the full 1mA source current must evaluate whether 300µA meets functional requirements or if the PCF8574PWR is more appropriate.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. Both PCF8574PWR and PCF8574TS/3,118 carry ROHS3 compliance certification, matching the original PCF8574PW specification.

Q: What is the MSL rating significance for these parts?

A: All three parts carry MSL rating 1 (Unlimited), indicating no moisture sensitivity restrictions during storage or handling. Standard PCB assembly processes are applicable without special moisture control requirements.

Q: Can these parts be used interchangeably in the same circuit?

A: Yes, provided the application does not require the specific 1mA source current specification. Both substitutes maintain I2C protocol compatibility, interrupt functionality, and power-on reset features. PCB layout considerations apply only when switching between 20-TSSOP and 20-LSSOP packages.

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