PCA8574TS,118 Equivalent & Substitute Parts

Part Overview

The PCA8574TS,118 is an 8-bit I/O Expander with I2C interface operating at 400 kHz, manufactured by NXP USA Inc. in a 20-SSOP package. This component is classified as Obsolete, which necessitates identification of functionally equivalent alternatives 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, operating across a supply voltage range of 2.3V to 5.5V and temperature range of -40°C to 85°C.

Key Parameters

Parameter	PCA8574TS,118
Number of I/O	8
Interface	I2C
Clock Frequency	400 kHz
Interrupt Output	Yes
Output Type	Push-Pull
Voltage Supply Range	2.3V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Mounting Type	Surface Mount
Package	20-LSSOP (0.173", 4.40mm Width)
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the PCA8574TS,118 is determined by the following critical parameters: 8 I/O lines, I2C interface protocol, push-pull output configuration, interrupt output capability, and surface mount technology. The substitute parts are grouped into two categories based on package compatibility and operational specifications:

Group 1: Direct Package Compatibility (20-SSOP/20-TSSOP) Parts maintaining the original 20-pin SSOP/TSSOP footprint with 8 I/O configuration and I2C interface. These substitutes operate at either 100 kHz or 400 kHz clock frequencies and maintain compatible voltage supply ranges.

Group 2: Alternative Package Formats (16-pin and 24-pin) Parts providing 8 I/O functionality with I2C interface in alternative package formats (16-TSSOP, 16-SOIC, 24-QSOP, 24-TQFN). These require PCB layout modification but offer enhanced thermal performance, extended temperature ranges, or automotive qualification.

Parameter Comparison

Part Number	Manufacturer	I/O Count	Interface	Clock Frequency	Voltage Supply	Operating Temperature	Package	Product Status
PCA8574TS,118	NXP USA Inc.	8	I2C	400 kHz	2.3V ~ 5.5V	-40°C ~ 85°C	20-LSSOP	Obsolete
PCF8574TS/3,118	NXP USA Inc.	8	I2C	100 kHz	2.5V ~ 6V	-40°C ~ 85°C	20-LSSOP	Active
PCF8574PWR	Texas Instruments	8	I2C	100 kHz	2.5V ~ 6V	-40°C ~ 85°C	20-TSSOP	Active
MAX7324AEG+T	Analog Devices Inc./Maxim Integrated	8	I2C	400 kHz	1.71V ~ 5.5V	-40°C ~ 125°C	24-QSOP	Active
MAX7324ATG+T	Analog Devices Inc./Maxim Integrated	8	I2C	400 kHz	1.71V ~ 5.5V	-40°C ~ 125°C	24-TQFN (4x4)	Active
TCA6408APWR	Texas Instruments	8	I2C, SMBus	400 kHz	1.65V ~ 5.5V	-40°C ~ 85°C	16-TSSOP	Active
TCA6408AQPWRQ1	Texas Instruments	8	I2C, SMBus	400 kHz	1.65V ~ 3.6V	-40°C ~ 125°C	16-TSSOP	Active
TCA6408ARGTR	Texas Instruments	8	I2C, SMBus	400 kHz	1.65V ~ 5.5V	-40°C ~ 85°C	16-VQFN (3x3)	Active
TCA9534DWR	Texas Instruments	8	I2C	400 kHz	1.65V ~ 5.5V	-40°C ~ 85°C	16-SOIC	Active
TCA9534DWT	Texas Instruments	8	I2C	400 kHz	1.65V ~ 5.5V	-40°C ~ 85°C	16-SOIC	Active

Engineering Selection Recommendations

For Direct Replacement (Minimal PCB Modification): PCF8574TS/3,118 or PCF8574PWR are recommended as primary substitutes. Both maintain 8 I/O configuration, I2C interface, and compatible package footprints. PCF8574TS/3,118 preserves the NXP manufacturer lineage with Active product status. PCF8574PWR offers Texas Instruments sourcing with equivalent functionality. Both are ROHS3 compliant with unlimited moisture sensitivity rating.

For 400 kHz Operation Requirement: If the application requires 400 kHz clock frequency operation, TCA9534DWR or TCA9534DWT provide direct functional equivalence with Active product status. These parts operate at 400 kHz matching the original PCA8574TS,118 specification and maintain I2C interface with 8 I/O configuration in 16-SOIC package.

For Extended Temperature Range: MAX7324AEG+T or MAX7324ATG+T support -40°C to 125°C operating range, exceeding the original -40°C to 85°C specification. These parts maintain 400 kHz I2C operation and 8 I/O functionality with Active product status and ROHS3 compliance. Package change to 24-pin format requires PCB redesign.

For Automotive Applications: TCA6408AQPWRQ1 provides AEC-Q100 automotive qualification with -40°C to 125°C operating range. This part maintains 8 I/O, 400 kHz I2C operation, and Active product status with ROHS3 compliance.

Frequently Asked Questions (FAQ)

Q: Can PCF8574TS/3,118 directly replace PCA8574TS,118 without PCB modification? A: Yes. Both parts share identical 20-LSSOP package footprint, 8 I/O configuration, I2C interface, and push-pull output type. The primary difference is clock frequency (100 kHz vs. 400 kHz). Verify application timing requirements before substitution.

Q: What is the difference between 100 kHz and 400 kHz I2C operation? A: Clock frequency determines I2C bus speed. 400 kHz operation provides faster data transfer rates. Applications designed for 400 kHz operation may experience timing issues with 100 kHz substitutes. Conversely, 400 kHz parts operate correctly in 100 kHz applications.

Q: Why do some substitutes have different package formats? A: Alternative packages (16-SOIC, 24-QSOP, 16-VQFN) provide different thermal characteristics, pin density, and manufacturing advantages. Package changes require PCB layout modification but may offer improved performance or cost benefits.

Q: Are TCA6408 and TCA9534 parts interchangeable? A: Both provide 8 I/O I2C expander functionality at 400 kHz. TCA6408 supports SMBus protocol in addition to I2C. TCA9534 operates I2C only. Verify protocol requirements in the application before substitution.

Q: What does ROHS3 compliance indicate? A: ROHS3 compliance certifies the part meets Restriction of Hazardous Substances Directive requirements, restricting lead, cadmium, mercury, and other hazardous materials. All listed substitutes maintain ROHS3 compliance.

Q: Can I use a substitute with lower voltage supply minimum (1.65V vs. 2.3V)? A: Yes, if your application operates within the substitute's voltage range. Lower minimum voltage specifications provide broader operational flexibility. Verify the application power supply voltage falls within the substitute's specified range.

Q: What is the significance of Moisture Sensitivity Level (MSL)? A: MSL 1 (Unlimited) indicates the part has no moisture sensitivity restrictions and requires no special handling. MSL 2 (1 Year) requires controlled storage conditions. All primary substitutes maintain MSL 1 rating.

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