PCA8574N,112 Equivalent & Substitute Parts

Part Overview

The PCA8574N,112 is an 8-bit I/O Expander with I2C interface operating at 400 kHz, manufactured by NXP USA Inc. in a 16-DIP through-hole package. This component is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. The part provides 8 I/O lines with push-pull output configuration, interrupt output capability, and power-on reset (POR) feature, suitable for applications requiring I2C-based digital I/O expansion in embedded systems.

Key Parameters

Parameter	Value
Number of I/O	8
Interface	I2C
Clock Frequency	400 kHz
Voltage Supply Range	2.3V ~ 5.5V
Output Type	Push-Pull
Interrupt Output	Yes
Features	POR
Operating Temperature	-40°C ~ 85°C
Mounting Type	Through Hole
Package	16-DIP (0.300", 7.62mm)
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the PCA8574N,112 is determined by the following critical parameters:

8 I/O Lines: All substitute parts must provide exactly 8 I/O channels
I2C Interface: Primary communication protocol; SMBus compatibility is acceptable as SMBus is a superset of I2C
400 kHz Clock Frequency: Minimum required operational speed
Push-Pull Output Configuration: Required for direct logic-level output driving
Interrupt Output: Must be present for interrupt-driven applications
POR Feature: Power-on reset functionality must be included
Voltage Supply Range: Substitute must operate within or exceed the 2.3V ~ 5.5V range
Operating Temperature Range: Must support -40°C ~ 85°C minimum

Substitute parts are grouped into two categories: through-hole packages (direct pin-compatible replacement) and surface-mount packages (functional equivalents requiring PCB redesign).

Parameter Comparison

Parameter	PCA8574N,112	PCF8574AN	TCA9534DWT	TCA6408ARSVR	MAX7324AEG+T
Number of I/O	8	8	8	8	8
Interface	I2C	I2C	I2C	I2C, SMBus	I2C
Clock Frequency	400 kHz	100 kHz	400 kHz	400 kHz	400 kHz
Voltage Supply Range	2.3V ~ 5.5V	2.5V ~ 6V	1.65V ~ 5.5V	1.65V ~ 5.5V	1.71V ~ 5.5V
Output Type	Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull
Interrupt Output	Yes	Yes	Yes	Yes	Yes
Features	POR	POR	-	POR	POR
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 125°C
Mounting Type	Through Hole	Through Hole	Surface Mount	Surface Mount	Surface Mount
Package	16-DIP	16-DIP	16-SOIC	16-UQFN	24-QSOP
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Through-Hole Direct Replacement:

PCF8574AN (Texas Instruments) is the primary through-hole substitute. It maintains identical 16-DIP package geometry and pin compatibility with the PCA8574N,112. Operating temperature range matches at -40°C ~ 85°C. Clock frequency operates at 100 kHz, which is lower than the original 400 kHz specification but remains suitable for standard I2C applications. Supply voltage range of 2.5V ~ 6V encompasses the original 2.3V ~ 5.5V specification. Product status is active with established supply chain availability.

Surface-Mount Alternatives:

For designs permitting PCB layout modification, three surface-mount options provide active product status and extended availability:

TCA9534DWT (Texas Instruments) in 16-SOIC package offers 400 kHz operation matching the original specification. Supply voltage range of 1.65V ~ 5.5V provides lower voltage capability. Product status is active with high inventory levels (45,300 units).

TCA6408ARSVR (Texas Instruments) in 16-UQFN package provides 400 kHz I2C and SMBus compatibility. Supply voltage range of 1.65V ~ 5.5V and operating temperature of -40°C ~ 85°C match original specifications. Product status is active with substantial inventory (35,300 units).

MAX7324AEG+T (Analog Devices Inc./Maxim Integrated) in 24-QSOP package operates at 400 kHz with extended temperature range of -40°C ~ 125°C. Supply voltage range of 1.71V ~ 5.5V supports lower voltage operation. Product status is active with high inventory availability (2,700 units in tape & reel packaging).

All substitute parts maintain ROHS3 compliance and REACH unaffected status consistent with the original component.

Frequently Asked Questions (FAQ)

Q: Can PCF8574AN replace PCA8574N,112 in existing designs?

A: Yes, for applications where 100 kHz I2C clock frequency is acceptable. PCF8574AN provides identical 16-DIP package pinout and through-hole mounting. If the original design requires 400 kHz operation, this substitute is not suitable.

Q: What is the primary difference between through-hole and surface-mount substitutes?

A: Through-hole substitutes (PCF8574AN) require no PCB redesign and can be directly soldered into existing board layouts. Surface-mount substitutes (TCA9534DWT, TCA6408ARSVR, MAX7324AEG+T) require PCB layout modification and surface-mount assembly processes but offer smaller footprints and extended product availability.

Q: Are SMBus-compatible parts (TCA6408ARSVR) fully compatible with I2C-only designs?

A: Yes. SMBus is a superset of I2C protocol. Parts supporting both I2C and SMBus operate as standard I2C devices in I2C-only applications without functional degradation.

Q: Which substitute offers the widest operating temperature range?

A: MAX7324AEG+T supports -40°C ~ 125°C, extending 40°C above the original PCA8574N,112 specification of -40°C ~ 85°C. This is beneficial for high-temperature industrial applications.

Q: Do all substitutes provide the same output current capability?

A: No. Output current specifications vary: PCA8574N,112 provides 100µA source and 25mA sink; PCF8574AN provides 1mA source and 25mA sink; TCA9534DWT specifications are not provided; TCA6408ARSVR provides 10mA source and 25mA sink; MAX7324AEG+T provides 20mA source and sink. Verify output current requirements for your application.

Q: Is the POR (Power-On Reset) feature present in all substitutes?

A: No. TCA9534DWT does not list POR as a feature. If power-on reset functionality is critical to your application, select from PCF8574AN, TCA6408ARSVR, or MAX7324AEG+T variants.

Q: What packaging options are available for the MAX7324 base product?

A: MAX7324 is available in three package variants: 24-QSOP (MAX7324AEG+, MAX7324AEG+T), and 24-TQFN (MAX7324ATG+, MAX7324ATG+T). Tube and tape & reel packaging options are available for both package types.

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