PCF8574AT/3,512 Equivalent & Substitute Parts

Part Overview

The PCF8574AT/3,512 is an 8-bit I/O expander with I2C interface operating at 100 kHz, housed in a 16-SOIC package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The device provides push-pull output configuration with interrupt capability and power-on reset (POR) feature, suitable for applications requiring remote I/O expansion over I2C bus architecture.

Key Parameters

Parameter	Value
Manufacturer	NXP Semiconductors
Number of I/O	8
Interface	I2C
Clock Frequency	100 kHz
Interrupt Output	Yes
Output Type	Push-Pull
Current - Output Source/Sink	300µA, 25mA
Voltage - Supply	2.5V ~ 6V
Operating Temperature	-40°C ~ 85°C
Package / Case	16-SOIC (0.295", 7.50mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the PCF8574AT/3,512 is determined by the following critical parameters:

Primary Substitution Criteria:

Number of I/O: 8 bits (exact match required)
Interface: I2C protocol compatibility
Clock Frequency: 100 kHz minimum
Output Type: Push-Pull configuration
Package: 16-SOIC form factor
Interrupt Output: Yes (required for functional equivalence)
Voltage Supply Range: Overlap with 2.5V ~ 6V
Operating Temperature: -40°C ~ 85°C minimum coverage

Substitution Categories:

Direct Equivalents (Same Base Product, Different Packaging): PCF8574AT/3,518 from NXP Semiconductors maintains identical electrical specifications with active product status and improved availability.

Compatible Alternatives (Same Electrical Function, Different Manufacturer): PCF8574ADW (Texas Instruments) provides equivalent I/O expansion with I2C 100 kHz operation in 16-SOIC package. Output source current differs (1mA vs 300µA), but sink current remains at 25mA.

Enhanced Alternatives (Higher Clock Frequency, Same Package): PCA9534ADW, PCA9534ADWR, and PCA9534DW (Texas Instruments) operate at 400 kHz I2C/SMBus with push-pull outputs, supporting both I2C and SMBus protocols. These parts maintain 8-bit I/O, interrupt capability, and 16-SOIC packaging.

Functional Alternatives (Different Package, Extended Features): MAX7329AWE+ and MAX7329AWE+T (Analog Devices/Maxim) provide 8-bit I2C I/O expansion at 100 kHz with open-drain output, extended temperature range (-40°C ~ 125°C), and 16-SOIC package. Interrupt output is supported.

MAX7328AWE+ (Analog Devices/Maxim) operates as 2-Wire I/O expander without interrupt output, suitable for applications not requiring interrupt signaling.

MAX1608EEE+ (Analog Devices/Maxim) provides SMBus interface alternative with open-drain output in 16-QSOP package, representing a different form factor option.

NLVPCA9535EDTR2G (onsemi) expands to 16-bit I/O with I2C interface at 100 kHz, suitable for applications requiring additional I/O expansion beyond 8 bits.

Parameter Comparison

Part Number	Manufacturer	I/O Count	Interface	Clock Freq	Output Type	Interrupt	Package	Voltage Supply	Temp Range	Product Status
PCF8574AT/3,512	NXP	8	I2C	100 kHz	Push-Pull	Yes	16-SOIC	2.5V ~ 6V	-40°C ~ 85°C	Obsolete
PCF8574AT/3,518	NXP	8	I2C	100 kHz	Push-Pull	Yes	16-SOIC	2.5V ~ 6V	-40°C ~ 85°C	Active
PCF8574ADW	Texas Instruments	8	I2C	100 kHz	Push-Pull	Yes	16-SOIC	2.5V ~ 6V	-40°C ~ 85°C	Obsolete
PCA9534ADW	Texas Instruments	8	I2C, SMBus	400 kHz	Push-Pull	Yes	16-SOIC	2.3V ~ 5.5V	-40°C ~ 85°C	Last Time Buy
PCA9534ADWR	Texas Instruments	8	I2C, SMBus	400 kHz	Push-Pull	Yes	16-SOIC	2.3V ~ 5.5V	-40°C ~ 85°C	Last Time Buy
PCA9534DW	Texas Instruments	8	I2C, SMBus	400 kHz	Push-Pull	Yes	16-SOIC	2.3V ~ 5.5V	-40°C ~ 85°C	Last Time Buy
MAX7329AWE+	Analog Devices/Maxim	8	I2C	100 kHz	Open Drain	Yes	16-SOIC	2.5V ~ 5.5V	-40°C ~ 125°C	Active
MAX7329AWE+T	Analog Devices/Maxim	8	I2C	100 kHz	Open Drain	Yes	16-SOIC	2.5V ~ 5.5V	-40°C ~ 125°C	Active
MAX7328AWE+	Analog Devices/Maxim	8	2-Wire	100 kHz	Open Drain	No	16-SOIC	2.5V ~ 5.5V	-40°C ~ 125°C	Active
MAX1608EEE+	Analog Devices/Maxim	8	SMBus	100 kHz	Open Drain	No	16-QSOP	2.7V ~ 5.5V	-40°C ~ 85°C	Active
NLVPCA9535EDTR2G	onsemi	16	I2C	100 kHz	Open Drain	Yes	24-TSSOP	1.65V ~ 5.5V	-55°C ~ 125°C	Obsolete

Engineering Selection Recommendations

Recommended Primary Substitute: PCF8574AT/3,518 (NXP Semiconductors) is the preferred direct equivalent. This part maintains identical electrical and mechanical specifications to the PCF8574AT/3,512 while offering active product status and significantly higher inventory availability (17,623 units in stock). Both parts are ROHS3 compliant and REACH unaffected, ensuring regulatory continuity.

Recommended Secondary Substitutes for Active Product Status: MAX7329AWE+ and MAX7329AWE+T (Analog Devices/Maxim) provide active product status with extended operating temperature range (-40°C ~ 125°C). Both maintain 8-bit I2C I/O expansion at 100 kHz with interrupt capability in 16-SOIC package. The primary design consideration is output type transition from push-pull to open-drain, which requires pull-up resistor implementation in the application circuit. Both variants are ROHS3 compliant with unlimited moisture sensitivity level.

Substitutes for Enhanced Performance Requirements: PCA9534ADW, PCA9534ADWR, and PCA9534DW (Texas Instruments) support 400 kHz I2C/SMBus operation with push-pull output configuration, maintaining functional compatibility with the original part. These parts are classified as Last Time Buy, indicating limited future availability. All three maintain 8-bit I/O, interrupt output, and 16-SOIC packaging with ROHS3 compliance.

Substitutes for Extended Temperature Applications: MAX7328AWE+ operates as 2-Wire I/O expander without interrupt output, suitable for applications not requiring interrupt signaling but requiring extended temperature range (-40°C ~ 125°C). This part is active and ROHS3 compliant.

Substitutes for Expanded I/O Requirements: NLVPCA9535EDTR2G (onsemi) provides 16-bit I/O expansion with I2C interface at 100 kHz, supporting applications requiring additional I/O beyond 8 bits. This part is classified as obsolete with extended temperature range (-55°C ~ 125°C) and operates across 1.65V ~ 5.5V supply voltage.

Substitutes for Alternative Package Requirements: MAX1608EEE+ (Analog Devices/Maxim) provides SMBus interface in 16-QSOP package, representing an alternative form factor for space-constrained applications. This part lacks interrupt output capability and operates without POR feature.

Frequently Asked Questions (FAQ)

Q: Can PCF8574AT/3,518 be used as a direct replacement for PCF8574AT/3,512?

A: Yes. PCF8574AT/3,518 is a direct electrical and mechanical equivalent with identical specifications. The primary difference is product status (active vs. obsolete) and packaging format (Cut Tape & Digi-Reel vs. standard packaging). No circuit modifications are required.

Q: What is the key difference between push-pull and open-drain output types?

A: Push-pull outputs (PCF8574AT/3,512, PCA9534 series) actively drive both high and low logic levels. Open-drain outputs (MAX7329 series) require external pull-up resistors to achieve high logic levels. Applications using push-pull outputs must be redesigned with pull-up resistors when substituting with open-drain alternatives.

Q: Are PCA9534 parts suitable substitutes despite 400 kHz clock frequency?

A: Yes, for most applications. The 400 kHz clock frequency is backward compatible with 100 kHz I2C bus operation. However, PCA9534 parts are classified as Last Time Buy, indicating limited future procurement availability. These parts maintain push-pull output configuration and interrupt capability, ensuring functional compatibility.

Q: Why does NLVPCA9535EDTR2G have 16 I/O instead of 8?

A: NLVPCA9535EDTR2G is a 16-bit I/O expander designed for applications requiring expanded I/O capacity. This part is suitable only for designs where additional I/O expansion is beneficial and the application can accommodate the 24-TSSOP package form factor.

Q: What are the compliance and regulatory considerations for substitution?

A: All listed substitute parts maintain ROHS3 compliance and REACH unaffected status, ensuring regulatory continuity with the original PCF8574AT/3,512. Moisture sensitivity levels vary (MSL 1 vs. MSL 2), affecting storage and handling requirements. Parts with MSL 1 (unlimited shelf life) provide superior long-term storage characteristics compared to MSL 2 (1-year shelf life).

Q: Can MAX7328AWE+ be used in applications requiring interrupt signaling?

A: No. MAX7328AWE+ operates as a 2-Wire I/O expander without interrupt output capability. This part is suitable only for applications not requiring interrupt-driven I/O notification. For interrupt-dependent designs, use MAX7329AWE+, MAX7329AWE+T, or other interrupt-capable alternatives.

Q: What packaging options are available for substitutes?

A: Most substitutes maintain 16-SOIC package compatibility with the original part. MAX1608EEE+ uses 16-QSOP package (smaller form factor). NLVPCA9535EDTR2G uses 24-TSSOP package (larger, 16-bit variant). Packaging selection depends on PCB layout constraints and I/O expansion requirements.

Q: Are there supply voltage compatibility concerns when substituting?

A: Yes. The original PCF8574AT/3,512 operates across 2.5V ~ 6V. Most substitutes operate within 2.3V ~ 5.5V or 2.5V ~ 5.5V ranges. Applications requiring 5.5V ~ 6V operation must verify substitute compatibility. NLVPCA9535EDTR2G extends to 1.65V ~ 5.5V, supporting lower voltage applications.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message