PCA8574ATS,112 Equivalent & Substitute Parts

Part Overview

The PCA8574ATS,112 is an 8-bit I/O expander interface circuit manufactured by NXP USA Inc., designed for I2C communication at 400 kHz in a 20-SSOP package. This part is classified as obsolete, which necessitates identification of active equivalent and substitute components for new designs and production continuity. The PCA8574ATS,112 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	PCA8574ATS,112
Number of I/O	8
Interface	I2C
Clock Frequency	400 kHz
Interrupt Output	Yes
Output Type	Push-Pull
Current - Output Source/Sink	100µA, 25mA
Voltage - Supply	2.3V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Package / Case	20-LSSOP (0.173", 4.40mm Width)
Mounting Type	Surface Mount
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the PCA8574ATS,112 is determined by the following critical parameters: 8 I/O lines, I2C interface protocol, 400 kHz clock frequency capability, push-pull output configuration, interrupt output functionality, and surface mount packaging. Substitute parts are grouped into three categories based on package compatibility and electrical performance alignment:

Group 1: Same Package Family (20-SSOP) - Direct Pin-Compatible Substitutes

PCF8574ATS/3,118: NXP equivalent with reduced clock frequency (100 kHz) but identical pin count and package footprint

Group 2: Alternative Packages with Equivalent Functionality (24-QSOP / 24-TQFN)

MAX7324AEG+T, MAX7324AEG+, MAX7324ATG+T: Maxim Integrated alternatives with 400 kHz operation, extended temperature range, and wider supply voltage tolerance

Group 3: Reduced Pin Count Packages (16-TSSOP / 16-SOIC / 16-SSOP / 16-VQFN)

TCA6408APWR, TCA6408AQPWRQ1, TCA6408ARGTR, TCA9534DWR, TCA9534PWR, TCA9538DBR: Texas Instruments alternatives with 8 I/O functionality in smaller packages

Substitution logic is based on maintaining 8 I/O count, I2C interface, 400 kHz operation (or compatible lower frequency), push-pull output, and interrupt capability. Package changes require PCB redesign but preserve functional compatibility.

Parameter Comparison

Parameter	PCA8574ATS,112	PCF8574ATS/3,118	MAX7324AEG+T	MAX7324ATG+T	TCA6408APWR	TCA9534PWR	TCA9538DBR
Number of I/O	8	8	8	8	8	8	8
Interface	I2C	I2C	I2C	I2C	I2C, SMBus	I2C	I2C
Clock Frequency	400 kHz	100 kHz	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz
Interrupt Output	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Output Type	Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull
Voltage - Supply	2.3V ~ 5.5V	2.5V ~ 6V	1.71V ~ 5.5V	1.71V ~ 5.5V	1.65V ~ 5.5V	1.65V ~ 5.5V	1.65V ~ 5.5V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Package / Case	20-LSSOP	20-LSSOP	24-SSOP	24-WFQFN	16-TSSOP	16-TSSOP	16-SSOP
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Product Status	Obsolete	Active	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Pin-Compatible Replacement (Same PCB Layout): PCF8574ATS/3,118 is the primary substitute when PCB redesign is not feasible. This NXP part maintains identical pin configuration and 20-LSSOP package footprint. The reduced clock frequency of 100 kHz is compatible with standard I2C bus operation. Product status is active with full availability (3400 pcs in stock). RoHS3 compliance and unlimited moisture sensitivity level (MSL 1) match the original specification.

For Enhanced Performance with Package Change: MAX7324AEG+T and MAX7324ATG+T offer extended operating temperature range (-40°C to 125°C) and wider supply voltage tolerance (1.71V to 5.5V). Both maintain 400 kHz clock frequency and full I/O functionality. MAX7324AEG+T uses 24-QSOP packaging (Tape & Reel), while MAX7324ATG+T uses 24-TQFN (4x4) packaging. Both are active products with strong inventory availability.

For Compact Package Alternatives: TCA6408APWR, TCA9534PWR, and TCA9538DBR provide 8 I/O functionality in 16-pin packages (TSSOP, SOIC, SSOP respectively). These Texas Instruments parts maintain 400 kHz I2C operation and are active products with high inventory levels. TCA6408APWR additionally supports SMBus protocol. All three are RoHS3 compliant with MSL 1 rating.

For Automotive Applications: TCA6408AQPWRQ1 is qualified to AEC-Q100 automotive standard with operating temperature range of -40°C to 125°C and supply voltage 1.65V to 3.6V. This part is suitable for automotive-grade designs requiring enhanced reliability specifications.

Frequently Asked Questions (FAQ)

Q: Can PCF8574ATS/3,118 directly replace PCA8574ATS,112 without PCB modification? A: Yes. PCF8574ATS/3,118 shares identical pin configuration and 20-LSSOP package footprint. The primary difference is reduced clock frequency (100 kHz vs. 400 kHz), which is compatible with standard I2C bus operation. No PCB layout changes are required.

Q: What is the impact of using a 100 kHz I2C device instead of 400 kHz? A: Clock frequency reduction affects maximum data transfer rate but does not impact functional compatibility. I2C bus operation at 100 kHz is standard and widely supported. System timing must accommodate the slower communication speed.

Q: Why do MAX7324 parts use different packages (24-QSOP vs. 24-TQFN)? A: MAX7324AEG+T uses 24-QSOP (Shrink Quad Flat Pack) for tape and reel packaging, while MAX7324ATG+T uses 24-TQFN (Thin Quad Flat No-Lead) for improved thermal performance. Both provide identical electrical functionality; package selection depends on assembly equipment and thermal requirements.

Q: Are Texas Instruments TCA parts pin-compatible with the PCA8574ATS,112? A: No. TCA parts use 16-pin packages (TSSOP, SOIC, SSOP, VQFN) versus the 20-pin LSSOP of the original part. PCB redesign is required. However, all maintain 8 I/O functionality and I2C interface compatibility.

Q: What is the difference between TCA6408APWR and TCA6408AQPWRQ1? A: TCA6408AQPWRQ1 is automotive-qualified (AEC-Q100) with restricted supply voltage range (1.65V to 3.6V) and extended temperature range (-40°C to 125°C). TCA6408APWR is industrial-grade with wider supply voltage (1.65V to 5.5V) and standard temperature range (-40°C to 85°C). Selection depends on application requirements.

Q: Can I use a substitute part with lower current output rating? A: Substitution is valid only if the application current requirements do not exceed the substitute part's output source/sink specification. Review system load requirements against each candidate part's current rating before selection.

Q: Are all substitute parts RoHS3 compliant? A: Yes. All listed substitute parts maintain ROHS3 compliance and REACH unaffected status, matching the environmental compliance profile of the original PCA8574ATS,112.

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