PCF8575PW I/O Expander 16-Bit I2C Interface

Part Overview

The PCF8575PW is a 16-bit I/O expander designed for I2C and SMBus communication at 400 kHz clock frequency. This device operates in the 4.5V to 5.5V supply range and features push-pull output configuration with 10mA source and 25mA sink current capability. The PCF8575PW is classified as obsolete, necessitating identification of active alternative components that maintain functional and electrical compatibility for new designs and production continuity.

Key Parameters

Parameter	Value
Manufacturer Part Number	PCF8575PW
Manufacturer	Texas Instruments
Number of I/O	16
Interface	I2C, SMBus
Clock Frequency	400 kHz
Voltage Supply Range	4.5V ~ 5.5V
Output Type	Push-Pull
Current Output Source/Sink	10mA / 25mA
Operating Temperature	-40°C ~ 85°C
Package	24-TSSOP
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the PCF8575PW is determined by the following critical parameters:

I/O Count: 16-bit configuration required
Interface Protocol: I2C or SMBus compatibility at 400 kHz
Package Type: Surface mount packages (24-TSSOP, 28-SOIC, 28-SSOP, 28-QFN)
Output Configuration: Push-pull output topology
Supply Voltage Compatibility: Minimum voltage support of 4.5V or lower
Current Drive Capability: Source and sink current specifications
Operating Temperature Range: -40°C to 85°C minimum
Compliance: ROHS3 and REACH compliance maintained

Substitute parts are grouped into two categories: direct pin-compatible replacements in 24-TSSOP packaging (PCF8575PWR, PCA9535 series, PCA9555 series) and functionally equivalent alternatives in alternative packages (MCP23016 series, MAX7312AUG+T).

Parameter Comparison

Part Number	Manufacturer	I/O Count	Interface	Clock Freq	Supply Voltage	Output Type	Current Source/Sink	Temp Range	Package	Status
PCF8575PW	Texas Instruments	16	I2C, SMBus	400 kHz	4.5V ~ 5.5V	Push-Pull	10mA / 25mA	-40°C ~ 85°C	24-TSSOP	Obsolete
PCF8575PWR	Texas Instruments	16	I2C, SMBus	400 kHz	2.5V ~ 5.5V	Push-Pull	1mA / 25mA	-40°C ~ 85°C	24-TSSOP	Active
PCA9535APW,118	NXP USA Inc.	16	I2C, SMBus	400 kHz	1.65V ~ 5.5V	Push-Pull	10mA / 25mA	-40°C ~ 85°C	24-TSSOP	Active
PCA9535PW,118	NXP USA Inc.	16	I2C, SMBus	400 kHz	2.3V ~ 5.5V	Push-Pull	10mA / 25mA	-40°C ~ 85°C	24-TSSOP	Active
PCA9555APW,118	NXP USA Inc.	16	I2C, SMBus	400 kHz	1.65V ~ 5.5V	Push-Pull	10mA / 25mA	-40°C ~ 85°C	24-TSSOP	Active
PCA9555PW,118	NXP USA Inc.	16	I2C, SMBus	400 kHz	2.3V ~ 5.5V	Push-Pull	10mA / 25mA	-40°C ~ 85°C	24-TSSOP	Active
MAX7312AUG+T	Analog Devices Inc./Maxim Integrated	16	I2C, SMBus	400 kHz	2V ~ 5.5V	Push-Pull	31mA / 43mA	-40°C ~ 125°C	24-TSSOP	Active
MCP23016-I/SO	Microchip Technology	16	I2C	400 kHz	2V ~ 5.5V	Push-Pull	25mA	-40°C ~ 85°C	28-SOIC	Active
MCP23016-I/ML	Microchip Technology	16	I2C	400 kHz	2V ~ 5.5V	Push-Pull	25mA	-40°C ~ 85°C	28-QFN (6x6)	Active
MCP23016T-I/ML	Microchip Technology	16	I2C	400 kHz	2V ~ 5.5V	Push-Pull	25mA	-40°C ~ 85°C	28-QFN (6x6)	Active
MCP23016T-I/SS	Microchip Technology	16	I2C	400 kHz	2V ~ 5.5V	Push-Pull	25mA	-40°C ~ 85°C	28-SSOP	Active

Engineering Selection Recommendations

Direct Pin-Compatible Replacement (24-TSSOP Package)

PCF8575PWR from Texas Instruments is the active equivalent of the obsolete PCF8575PW, maintaining identical pinout and package. This part extends supply voltage range to 2.5V minimum and is recommended as the primary replacement for existing PCF8575PW designs.

PCA9535 and PCA9555 series from NXP USA Inc. provide 24-TSSOP pin-compatible alternatives with extended supply voltage ranges (1.65V minimum for APW variants, 2.3V for PW variants). Both series maintain 400 kHz I2C/SMBus operation and push-pull output configuration. PCA9555 variants offer identical electrical specifications to PCA9535 with different internal register mapping.

Enhanced Performance Alternative (24-TSSOP Package)

MAX7312AUG+T from Analog Devices Inc./Maxim Integrated offers superior current drive capability (31mA source, 43mA sink) and extended operating temperature range (-40°C to 125°C) in 24-TSSOP packaging. This part is suitable for applications requiring higher output current or wider temperature operation.

Alternative Package Options (28-Pin Packages)

MCP23016 series from Microchip Technology provides 16-bit I2C I/O expansion in 28-SOIC, 28-SSOP, and 28-QFN packages. These parts maintain 400 kHz I2C operation with 25mA output current and -40°C to 85°C temperature range. Package selection depends on PCB layout and thermal requirements.

All substitute parts maintain ROHS3 compliance and REACH unaffected status consistent with the original PCF8575PW specification.

Frequently Asked Questions (FAQ)

Q: Can PCF8575PWR directly replace PCF8575PW without PCB modification?

A: Yes. PCF8575PWR maintains identical 24-TSSOP pinout and electrical interface. The extended supply voltage range (2.5V minimum versus 4.5V) provides additional design flexibility without requiring circuit changes.

Q: What is the functional difference between PCA9535 and PCA9555 series?

A: Both series provide identical 16-bit I2C/SMBus I/O expansion in 24-TSSOP packaging with matching electrical specifications. The difference lies in internal register organization and control logic. Selection depends on firmware compatibility with existing PCA9535 or PCA9555 driver code.

Q: Why do MCP23016 parts use different package options?

A: MCP23016 is available in 28-SOIC, 28-SSOP, and 28-QFN packages to accommodate different PCB design requirements. The 28-pin package provides additional ground and power distribution compared to 24-TSSOP, improving thermal and electrical performance in high-current applications.

Q: Is MAX7312AUG+T suitable for 5V-only systems?

A: Yes. MAX7312AUG+T operates across 2V to 5.5V supply range, fully compatible with 5V systems. The enhanced current drive (31mA/43mA) and extended temperature range (-40°C to 125°C) make it suitable for demanding industrial applications.

Q: What supply voltage must be maintained for all substitute parts?

A: All substitute parts operate at 5.5V maximum. Minimum supply voltage varies: PCF8575PWR requires 2.5V minimum, PCA9535/PCA9555 variants require 1.65V to 2.3V minimum, MCP23016 requires 2V minimum, and MAX7312AUG+T requires 2V minimum. Verify system supply voltage compatibility before selection.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance and REACH unaffected status, meeting environmental and regulatory requirements equivalent to the original PCF8575PW.

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