PCA8574AD,512 Equivalent & Substitute Parts

Part Overview

The PCA8574AD,512 is an 8-bit I/O expander with I2C interface operating at 400 kHz, manufactured by NXP USA Inc. in a 16-SOIC package. This component is classified as Obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. 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
Current Output Source/Sink	100µA, 25mA
Interrupt Output	Yes
Operating Temperature	-40°C ~ 85°C
Package Type	16-SOIC (0.295", 7.50mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution for the PCA8574AD,512 is determined by the following critical parameters:

I/O Count: Must be 8 bits
Interface Protocol: Must support I2C
Clock Frequency: 400 kHz operation required for direct replacement
Output Configuration: Push-pull output type
Interrupt Capability: Interrupt output required
Supply Voltage Compatibility: Minimum 2.3V support required
Package Compatibility: 16-SOIC package preferred for PCB layout compatibility; alternative packages acceptable if electrical specifications align
Compliance: ROHS3 compliance required

Substitute parts are grouped into two categories:

Category A - Direct Package Replacement (16-SOIC): Parts maintaining the same 16-SOIC package footprint, enabling direct PCB substitution without layout modification.

Category B - Functional Equivalents (Alternative Packages): Parts meeting all electrical specifications but in different packages (24-QSOP, 24-TQFN, 16-TSSOP, 16-VQFN, 16-UQFN), requiring PCB redesign but offering enhanced performance or availability.

Parameter Comparison

Part Number	Manufacturer	I/O Count	Interface	Clock Frequency	Supply Voltage	Output Type	Current Output (Source/Sink)	Interrupt Output	Package	Product Status
PCA8574AD,512	NXP USA Inc.	8	I2C	400 kHz	2.3V ~ 5.5V	Push-Pull	100µA, 25mA	Yes	16-SOIC	Obsolete
PCF8574AT/3,518	NXP Semiconductors	8	I2C	100 kHz	2.5V ~ 6V	Push-Pull	300µA, 25mA	Yes	16-SOIC	Active
MAX7324AEG+T	Analog Devices Inc./Maxim Integrated	8	I2C	400 kHz	1.71V ~ 5.5V	Push-Pull	20mA	Yes	24-QSOP	Active
MAX7324ATG+	Analog Devices Inc./Maxim Integrated	8	I2C	400 kHz	1.71V ~ 5.5V	Push-Pull	20mA	Yes	24-TQFN (4x4)	Active
PCA9554DW	Texas Instruments	8	I2C, SMBus	400 kHz	2.3V ~ 5.5V	Push-Pull	10mA, 25mA	Yes	16-SOIC	Last Time Buy
PCF8574ADW	Texas Instruments	8	I2C	100 kHz	2.5V ~ 6V	Push-Pull	1mA, 25mA	Yes	16-SOIC	Obsolete
TCA6408APWR	Texas Instruments	8	I2C, SMBus	400 kHz	1.65V ~ 5.5V	Push-Pull	10mA, 25mA	Yes	16-TSSOP	Active
TCA6408AQPWRQ1	Texas Instruments	8	I2C, SMBus	400 kHz	1.65V ~ 3.6V	Push-Pull	10mA, 25mA	Yes	16-TSSOP	Active
TCA6408ARGTR	Texas Instruments	8	I2C, SMBus	400 kHz	1.65V ~ 5.5V	Push-Pull	10mA, 25mA	Yes	16-VQFN (3x3)	Active
TCA6408ARSVR	Texas Instruments	8	I2C, SMBus	400 kHz	1.65V ~ 5.5V	Push-Pull	10mA, 25mA	Yes	16-UQFN (2.6x1.8)	Active
TCA9534ADWR	Texas Instruments	8	I2C	400 kHz	1.65V ~ 5.5V	Push-Pull	Not specified	Yes	16-SOIC	Active

Engineering Selection Recommendations

For Direct PCB Replacement (No Layout Modification Required)

PCA9554DW is the primary substitute for the PCA8574AD,512 when maintaining the 16-SOIC package footprint. Both parts operate at 400 kHz I2C clock frequency with identical supply voltage range (2.3V ~ 5.5V) and matching package dimensions. PCA9554DW is in Last Time Buy status, indicating limited availability but current production support. This part adds SMBus compatibility, which does not affect I2C-only applications.

TCA9534ADWR provides an alternative 16-SOIC option with Active product status, ensuring long-term availability. Operating specifications align with the original part at 400 kHz I2C frequency and 1.65V ~ 5.5V supply range. This part is recommended for new designs requiring extended product lifecycle support.

For New Designs with Package Flexibility

TCA6408APWR is recommended for applications where package size reduction is beneficial. This Active part operates at 400 kHz in a 16-TSSOP package with lower supply voltage floor (1.65V) and maintains SMBus compatibility. High inventory availability (58,400 pcs) supports production continuity.

TCA6408AQPWRQ1 is specified for automotive applications requiring AEC-Q100 qualification. This part maintains 400 kHz operation with restricted supply range (1.65V ~ 3.6V) suitable for 3.3V systems and includes automotive-grade reliability certification.

MAX7324AEG+T and MAX7324ATG+ offer 400 kHz operation with extended temperature range (-40°C ~ 125°C) compared to the original part (-40°C ~ 85°C). These Analog Devices parts require PCB redesign due to alternative packages (24-QSOP and 24-TQFN respectively) but provide enhanced thermal performance and lower supply voltage floor (1.71V).

Parts Not Recommended for Direct Substitution

PCF8574AT/3,518 and PCF8574ADW operate at 100 kHz clock frequency, which is incompatible with the 400 kHz specification of the original part. These parts are suitable only for applications where reduced I2C bus speed is acceptable.

Frequently Asked Questions (FAQ)

Q: Can PCF8574AT/3,518 replace PCA8574AD,512 in existing designs?

A: No. PCF8574AT/3,518 operates at 100 kHz I2C clock frequency, while PCA8574AD,512 operates at 400 kHz. Direct substitution will result in I2C bus speed mismatch and potential communication failures. This part is suitable only for new designs where 100 kHz operation is acceptable.

Q: What is the difference between PCA9554DW and TCA9534ADWR?

A: Both parts maintain 16-SOIC package compatibility and 400 kHz I2C operation. PCA9554DW is in Last Time Buy status with SMBus support, while TCA9534ADWR is Active with I2C-only interface. TCA9534ADWR is preferred for new designs requiring extended product availability.

Q: Can I use TCA6408APWR as a drop-in replacement?

A: TCA6408APWR is not a drop-in replacement due to different package (16-TSSOP vs. 16-SOIC). PCB redesign is required. However, all electrical specifications are compatible, including 400 kHz I2C operation and push-pull output configuration. This part is suitable for new PCB designs.

Q: What is the advantage of MAX7324 series parts?

A: MAX7324AEG+T and MAX7324ATG+ provide extended operating temperature range (-40°C ~ 125°C vs. -40°C ~ 85°C) and lower minimum supply voltage (1.71V). These parts require PCB redesign due to alternative packages but offer enhanced thermal performance for demanding applications.

Q: Is TCA6408AQPWRQ1 suitable for consumer applications?

A: TCA6408AQPWRQ1 is specifically qualified for automotive applications (AEC-Q100) with restricted supply voltage range (1.65V ~ 3.6V). While it functions in consumer applications, TCA6408APWR is the appropriate choice for non-automotive designs, offering full 5.5V supply voltage support.

Q: What packaging options are available for 400 kHz I2C operation?

A: 400 kHz operation is available in 16-SOIC (PCA9554DW, TCA9534ADWR), 16-TSSOP (TCA6408APWR, TCA6408AQPWRQ1), 16-VQFN (TCA6408ARGTR), 16-UQFN (TCA6408ARSVR), 24-QSOP (MAX7324AEG+T), and 24-TQFN (MAX7324ATG+) packages. Package selection depends on PCB layout constraints and thermal requirements.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed maintain ROHS3 compliance, matching the environmental certification of the original PCA8574AD,512.

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