CAT9554WI-GT2 Equivalent & Substitute Parts

Part Overview

The CAT9554WI-GT2 is an 8-channel I/O expander IC designed for I2C and SMBus communication at 400 kHz, packaged in a 16-SOIC surface mount configuration. Manufactured by onsemi, this component operates across a 2.3V to 5.5V supply range with push-pull output capability and integrated power-on reset (POR) functionality. The part is currently classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing system support and new design implementations.

Key Parameters

Parameter	CAT9554WI-GT2 Value
Number of I/O Channels	8
Interface Protocol	I2C, SMBus
Clock Frequency	400 kHz
Supply Voltage Range	2.3V – 5.5V
Output Type	Push-Pull
Current Output Source/Sink	10mA / 24mA
Operating Temperature Range	-40°C to +85°C
Package Type	16-SOIC (0.154", 3.90mm Width)
Interrupt Output	Yes
Features	POR
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution eligibility for the CAT9554WI-GT2 is determined by the following critical parameters:

Primary Matching Criteria:

8 I/O channels (mandatory)
I2C interface support (mandatory)
400 kHz clock frequency (mandatory for protocol compatibility)
Push-pull output configuration (mandatory)
Power-on reset feature (mandatory)
Surface mount technology (mandatory)

Secondary Compatibility Factors:

Supply voltage range must encompass or exceed 2.3V minimum
Operating temperature range must support -40°C to +85°C minimum
Package form factor (16-SOIC preferred for direct PCB compatibility; alternative packages acceptable with board redesign)
Output current capability (10mA source / 24mA sink baseline)

Substitute parts are grouped into two categories: direct package equivalents (16-SOIC) and functional equivalents with alternative packaging (TSSOP, UQFN, QSOP, TQFN). All listed substitutes maintain the 8-channel I/O, I2C protocol, 400 kHz operation, and push-pull output requirements.

Parameter Comparison

Parameter	CAT9554WI-GT2	PCA9654EDR2G	MAX7324AEG+T	MAX7324ATG+T	PCA9554DWR	TCA6408APWR	TCA6408ARSVR	TCA9534ADWR	TCA9534ADWT	TCA9534PWR
Number of I/O	8	8	8	8	8	8	8	8	8	8
Interface	I2C, SMBus	I2C	I2C	I2C	I2C, SMBus	I2C, SMBus	I2C, SMBus	I2C	I2C	I2C
Clock Frequency	400 kHz	100 kHz	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz
Supply Voltage Range	2.3V – 5.5V	1.65V – 5.5V	1.71V – 5.5V	1.71V – 5.5V	2.3V – 5.5V	1.65V – 5.5V	1.65V – 5.5V	1.65V – 5.5V	1.65V – 5.5V	1.65V – 5.5V
Output Type	Push-Pull	—	Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull
Current Output Source/Sink	10mA / 24mA	—	20mA	20mA	10mA / 25mA	10mA / 25mA	10mA / 25mA	—	—	10mA / 25mA
Operating Temperature	-40°C to +85°C	-55°C to +125°C	-40°C to +125°C	-40°C to +125°C	-40°C to +85°C	-40°C to +85°C	-40°C to +85°C	-40°C to +85°C	-40°C to +85°C	-40°C to +85°C
Package Type	16-SOIC (0.154", 3.90mm)	16-SOIC (0.154", 3.90mm)	24-QSOP (0.154", 3.90mm)	24-TQFN (4x4)	16-SOIC (0.295", 7.50mm)	16-TSSOP (0.173", 4.40mm)	16-UQFN (2.6x1.8)	16-SOIC (0.295", 7.50mm)	16-SOIC (0.295", 7.50mm)	16-TSSOP (0.173", 4.40mm)
Interrupt Output	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Product Status	Obsolete	Obsolete	Active	Active	Obsolete	Active	Active	Active	Active	Active
RoHS Compliance	—	ROHS3	ROHS3	ROHS3	ROHS3	ROHS3	ROHS3	ROHS3	ROHS3	ROHS3

Engineering Selection Recommendations

Direct Package Equivalents (16-SOIC, 0.154" Width):

PCA9654EDR2G is a direct package match but operates at 100 kHz clock frequency, which is incompatible with the 400 kHz requirement of the original CAT9554WI-GT2. This part is not suitable for direct substitution.

Functional Equivalents with Matching Electrical Specifications:

PCA9554DWR (Texas Instruments) provides identical electrical and functional characteristics to the CAT9554WI-GT2, including 400 kHz I2C/SMBus operation, 2.3V–5.5V supply range, and push-pull output. The package is 16-SOIC but with 0.295" width (7.50mm) versus the original 0.154" width. This part is obsolete but functionally equivalent.

TCA9534ADWR and TCA9534ADWT (Texas Instruments) match the 400 kHz I2C operation, push-pull output, and temperature range. Both are active products with ROHS3 compliance. Package is 16-SOIC (0.295" width). Supply voltage range is 1.65V–5.5V, which encompasses the original specification.

TCA9534PWR (Texas Instruments) provides equivalent functionality in 16-TSSOP packaging. Active product status and ROHS3 compliance support long-term availability.

Alternative Package Options for Space-Constrained Designs:

TCA6408APWR and TCA6408ARSVR (Texas Instruments) deliver 400 kHz I2C/SMBus operation with active product status and ROHS3 compliance. TCA6408APWR uses 16-TSSOP packaging; TCA6408ARSVR uses 16-UQFN (2.6x1.8) for compact applications. Both support 1.65V–5.5V supply range.

MAX7324AEG+T and MAX7324ATG+T (Analog Devices Inc./Maxim Integrated) provide 400 kHz I2C operation with active product status and ROHS3 compliance. These parts use 24-pin packages (QSOP and TQFN respectively), requiring PCB redesign but offering extended temperature range (-40°C to +125°C) and higher output current (20mA).

Selection Priority:

For direct replacement with minimal PCB modification: TCA9534ADWR or TCA9534ADWT (active, ROHS3 compliant, 16-SOIC package).

For compact designs: TCA6408ARSVR (active, ROHS3 compliant, 16-UQFN package).

For extended temperature applications: MAX7324ATG+T (active, ROHS3 compliant, 24-TQFN package).

Frequently Asked Questions (FAQ)

Q: Can PCA9654EDR2G replace the CAT9554WI-GT2?

A: No. Although PCA9654EDR2G matches the 16-SOIC package and 8-channel I/O configuration, it operates at 100 kHz clock frequency. The CAT9554WI-GT2 requires 400 kHz operation. This frequency mismatch makes PCA9654EDR2G incompatible for direct substitution.

Q: What is the primary difference between 16-SOIC (0.154" width) and 16-SOIC (0.295" width) packages?

A: Both are 16-pin SOIC packages, but the 0.295" width variant has wider pin spacing and larger overall dimensions. If the original PCB footprint is designed for 0.154" width, a 0.295" width part will not fit without PCB redesign. Verify footprint compatibility before selection.

Q: Are TCA9534 series parts fully compatible with CAT9554WI-GT2?

A: TCA9534ADWR, TCA9534ADWT, and TCA9534PWR match the 400 kHz I2C operation, push-pull output, and temperature range of the CAT9554WI-GT2. The primary difference is that TCA9534 parts support I2C only, while the original supports both I2C and SMBus. If SMBus protocol is not required, TCA9534 parts are fully compatible. All three are active products with ROHS3 compliance.

Q: Why do some substitute parts have wider supply voltage ranges (1.65V vs. 2.3V)?

A: Newer designs often extend the lower supply voltage limit to support a broader range of applications. A part rated for 1.65V–5.5V can operate in any system designed for 2.3V–5.5V, making it a compatible substitute. The wider range provides additional design flexibility without compromising compatibility.

Q: Can I use MAX7324 parts as direct replacements?

A: MAX7324AEG+T and MAX7324ATG+T provide equivalent I2C 400 kHz operation and push-pull output. However, both use 24-pin packages (QSOP and TQFN) instead of the original 16-SOIC, requiring PCB redesign. These parts are suitable for new designs or systems where PCB modification is acceptable. Both are active products with extended temperature range and ROHS3 compliance.

Q: What is the advantage of TCA6408ARSVR over other substitutes?

A: TCA6408ARSVR uses a compact 16-UQFN (2.6x1.8) package, offering significant space savings compared to SOIC or TSSOP alternatives. It maintains 400 kHz I2C/SMBus operation, push-pull output, and active product status with ROHS3 compliance. This part is ideal for space-constrained applications where PCB redesign is feasible.

Q: Are all listed substitutes RoHS3 compliant?

A: All substitute parts listed are ROHS3 compliant except the original CAT9554WI-GT2, for which RoHS status is not specified. ROHS3 compliance ensures compliance with current environmental and hazardous substance regulations.

Q: What should I verify before selecting a substitute part?

A: Confirm the following: (1) PCB footprint compatibility with the selected package type; (2) I2C or SMBus protocol requirement; (3) Operating temperature range suitability; (4) Supply voltage range compatibility; (5) Output current requirements; (6) Long-term availability and product status (active vs. obsolete).

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