PCAL9538ABS,128 I/O Expander Equivalent & Substitute Parts

Part Overview

The PCAL9538ABS,128 is an 8-channel I/O expander with I2C interface operating at 400 kHz, manufactured by NXP USA Inc. in a 16-HVQFN (3x3) package. This component is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. The part provides open drain and push-pull output configurations with interrupt output capability and power-on reset (POR) feature.

Key Parameters

Parameter	Value
Manufacturer Part Number	PCAL9538ABS,128
Manufacturer	NXP USA Inc.
Category	Interface
Number of I/O	8
Interface	I2C
Clock Frequency	400 kHz
Voltage Supply Range	1.65V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Output Type	Open Drain, Push-Pull
Current Output Source/Sink	10mA, 25mA
Interrupt Output	Yes
Features	POR
Package / Case	16-VFQFN Exposed Pad
Mounting Type	Surface Mount
Product Status	Obsolete
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution for the PCAL9538ABS,128 is determined by the following critical parameters:

Core Functional Requirements:

8 I/O channels
I2C interface at 400 kHz clock frequency
Interrupt output capability
Power-on reset (POR) feature
Supply voltage range: 1.65V ~ 5.5V
Operating temperature: -40°C ~ 85°C
Push-pull output capability

Package Compatibility Considerations: Substitute parts are grouped by package type. The original PCAL9538ABS,128 uses 16-HVQFN (3x3). Substitutes may use alternative packages (16-TSSOP, 16-SOIC, 24-QSOP, 24-TQFN) provided all electrical parameters remain compatible.

Manufacturer Variants: Substitutes from NXP, Texas Instruments, and Analog Devices Inc./Maxim Integrated are included based on matching electrical specifications and compliance certifications.

Parameter Comparison

Parameter	PCAL9538ABS,128	PCAL6408ABSHP	MAX7324AEG+T	TCA6408APWR	TCA9534ADWT	TCA9534PWR
Manufacturer	NXP USA Inc.	NXP USA Inc.	Analog Devices Inc./Maxim Integrated	Texas Instruments	Texas Instruments	Texas Instruments
Number of I/O	8	8	8	8	8	8
Interface	I2C	I2C, SMBus	I2C	I2C, SMBus	I2C	I2C
Clock Frequency	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz
Voltage Supply Range	1.65V ~ 5.5V	1.65V ~ 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 ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Output Type	Open Drain, Push-Pull	Open Drain, Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull
Current Output Source/Sink	10mA, 25mA	10mA, 25mA	20mA	10mA, 25mA	Not specified	10mA, 25mA
Interrupt Output	Yes	Yes	Yes	Yes	Yes	Yes
Features	POR	POR	POR	POR	Not specified	Not specified
Package / Case	16-VFQFN Exposed Pad	16-VFQFN Exposed Pad	24-SSOP (0.154", 3.90mm Width)	16-TSSOP (0.173", 4.40mm Width)	16-SOIC (0.295", 7.50mm Width)	16-TSSOP (0.173", 4.40mm Width)
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Primary Substitute - NXP PCAL6408ABSHP: The PCAL6408ABSHP is the closest functional equivalent, maintaining identical electrical specifications and package form factor (16-HVQFN). This part is currently in active production status with 8,123 units in stock. It adds SMBus compatibility while retaining full I2C 400 kHz operation. Recommended for direct replacement in existing designs.

Texas Instruments TCA9534 Series (ADWT, DWR, DWT, PWR): The TCA9534 variants provide full electrical compatibility with the PCAL9538ABS,128 across all critical parameters. These parts are available in multiple package options (16-SOIC, 16-TSSOP) with high inventory levels (1,646 to 165,200 units). All variants maintain the 400 kHz I2C interface, 1.65V ~ 5.5V supply range, and -40°C ~ 85°C operating temperature. Package selection depends on PCB layout requirements.

Texas Instruments TCA6408APWR: The TCA6408APWR offers SMBus compatibility in addition to I2C operation, with identical electrical specifications to the original part. Available in 16-TSSOP package with 58,400 units in stock. Suitable for applications requiring SMBus protocol support.

Analog Devices MAX7324 Series (AEG+, AEG+T, ATG+, ATG+T): The MAX7324 variants provide extended operating temperature range (-40°C ~ 125°C) compared to the original part. These parts are available in 24-QSOP and 24-TQFN packages. Output current capability is specified at 20mA. Selection among variants depends on packaging requirements (tube vs. tape & reel) and PCB footprint compatibility. Inventory ranges from 979 to 2,700 units.

Compliance and Certification: All substitute parts maintain ROHS3 compliance, MSL Level 1 (Unlimited), and EAR99 export classification, matching the original part's regulatory status.

Frequently Asked Questions (FAQ)

Q: Can I use the PCAL6408ABSHP as a direct replacement for the PCAL9538ABS,128?

A: Yes. The PCAL6408ABSHP maintains identical electrical specifications, package form factor (16-HVQFN), and supply voltage range (1.65V ~ 5.5V). The addition of SMBus compatibility does not affect I2C-only applications. Both parts operate at 400 kHz with 8 I/O channels and interrupt output capability.

Q: What is the difference between the TCA9534 variants (ADWT, DWR, DWT, PWR)?

A: The variants differ in packaging and tape format. ADWT and DWT use 16-SOIC packages in tape & reel and cut tape formats respectively. DWR and PWR use 16-TSSOP packages in cut tape and cut tape & digi-reel formats respectively. All variants maintain identical electrical specifications and are functionally interchangeable.

Q: Why do the MAX7324 parts have a higher operating temperature range?

A: The MAX7324 series is rated for -40°C ~ 125°C operation, compared to the original part's -40°C ~ 85°C. This extended range is a design characteristic of the Analog Devices MAX7324 family and does not affect compatibility in applications operating within the original temperature range.

Q: Are there package compatibility considerations when selecting a substitute?

A: Yes. The original PCAL9538ABS,128 uses a 16-HVQFN (3x3) package. Substitutes are available in 16-HVQFN (PCAL6408ABSHP), 16-SOIC (TCA9534 variants), 16-TSSOP (TCA6408APWR, TCA9534PWR), 24-QSOP, and 24-TQFN packages. PCB layout and footprint requirements determine which package option is suitable for your application.

Q: Do all substitute parts support both open drain and push-pull outputs?

A: No. The original PCAL9538ABS,128 and PCAL6408ABSHP support both open drain and push-pull outputs. The Texas Instruments TCA9534 and TCA6408 series, along with the Analog Devices MAX7324 series, support push-pull output only. Verify your application's output configuration requirements before selection.

Q: What is the inventory status of these substitute parts?

A: PCAL6408ABSHP has 8,123 units in stock. TCA9534 variants range from 1,646 to 165,200 units. TCA6408APWR has 58,400 units. MAX7324 variants range from 979 to 2,700 units. All parts are listed as new original stock.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts listed maintain ROHS3 compliance and MSL Level 1 (Unlimited) moisture sensitivity rating, matching the original part's regulatory status.

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