PCAL9554CBS,128 I/O Expander Equivalent & Substitute Parts

Part Overview

The PCAL9554CBS,128 is an 8-channel I/O expander with I2C and SMBus interface operating at 400 kHz, manufactured by NXP USA Inc. in a 16-HVQFN (3x3) package. This component is classified as obsolete, necessitating identification of active equivalent and substitute parts for new designs and production continuity. Substitute parts maintain functional compatibility through matching electrical specifications and interface protocols while offering improved availability and extended product lifecycle support.

Key Parameters

Parameter	PCAL9554CBS,128
Number of I/O	8
Interface	I2C, SMBus
Clock Frequency	400 kHz
Interrupt Output	Yes
Output Type	Open Drain, Push-Pull
Current - Output Source/Sink	10mA, 25mA
Voltage - Supply	1.65V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Mounting Type	Surface Mount
Package / Case	16-VFQFN Exposed Pad
RoHS Status	ROHS3 Compliant
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitute parts are grouped based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are: 8-channel I/O count, I2C interface at 400 kHz clock frequency, interrupt output capability, push-pull output configuration, supply voltage range compatibility, and surface mount technology. Package form factor variations (16-HVQFN, 16-TSSOP, 16-SOIC, 24-QSOP, 24-TQFN) represent mechanical alternatives that maintain functional equivalence when PCB layout permits package substitution.

Substitute parts are categorized as follows:

Group 1 - Direct Package Equivalent (16-HVQFN): PCAL6408ABSHP maintains identical package geometry and pinout compatibility with the original part.

Group 2 - Alternative Package, Equivalent Function (16-TSSOP, 16-UQFN, 16-SOIC): TCA6408APWR, TCA6408AQPWRQ1, TCA6408ARSVR, TCA9534ADWR, and TCA9534ADWT provide functional equivalence with different package footprints suitable for alternative PCB designs.

Group 3 - Extended Feature Set (24-QSOP, 24-TQFN): MAX7324AEG+, MAX7324AEG+T, MAX7324ATG+, and MAX7324ATG+T offer enhanced output current capability (20mA) and extended operating temperature range (-40°C ~ 125°C) in larger packages.

Parameter Comparison

Parameter	PCAL9554CBS,128	PCAL6408ABSHP	TCA6408APWR	TCA6408AQPWRQ1	TCA6408ARSVR	TCA9534ADWR	TCA9534ADWT	MAX7324AEG+	MAX7324AEG+T	MAX7324ATG+	MAX7324ATG+T
Number of I/O	8	8	8	8	8	8	8	8	8	8	8
Interface	I2C, SMBus	I2C, SMBus	I2C, SMBus	I2C, SMBus	I2C, SMBus	I2C	I2C	I2C	I2C	I2C	I2C
Clock Frequency	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz	400 kHz
Interrupt Output	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Output Type	Open Drain, Push-Pull	Open Drain, Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull	Push-Pull
Current - Output Source/Sink	10mA, 25mA	10mA, 25mA	10mA, 25mA	10mA, 25mA	10mA, 25mA	—	—	20mA	20mA	20mA	20mA
Voltage - Supply	1.65V ~ 5.5V	1.65V ~ 5.5V	1.65V ~ 5.5V	1.65V ~ 3.6V	1.65V ~ 5.5V	1.65V ~ 5.5V	1.65V ~ 5.5V	1.71V ~ 5.5V	1.71V ~ 5.5V	1.71V ~ 5.5V	1.71V ~ 5.5V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 125°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C
Package / Case	16-VFQFN Exposed Pad	16-VFQFN Exposed Pad	16-TSSOP	16-TSSOP	16-UFQFN	16-SOIC	16-SOIC	24-SSOP	24-SSOP	24-WFQFN Exposed Pad	24-WFQFN Exposed Pad
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active	Active	Active	Active

Engineering Selection Recommendations

PCAL6408ABSHP is the primary direct replacement, offering identical electrical specifications and package geometry with active product status and superior inventory availability (8123 pcs). This part is recommended for designs requiring minimal PCB modification.

TCA6408APWR, TCA6408ARSVR are suitable alternatives from Texas Instruments with extensive inventory (58400 pcs and 35300 pcs respectively) and active status. TCA6408APWR uses 16-TSSOP packaging; TCA6408ARSVR uses 16-UQFN (2.6x1.8) for space-constrained applications. Both maintain full electrical compatibility with the original part.

TCA6408AQPWRQ1 is qualified to AEC-Q100 automotive standard with extended operating temperature range (-40°C ~ 125°C) and reduced supply voltage range (1.65V ~ 3.6V). Selection requires confirmation of voltage compatibility with target application.

TCA9534ADWR and TCA9534ADWT provide 16-SOIC packaging alternative with active status. These parts lack specified output current ratings and SMBus interface support, suitable only for applications not requiring these features.

MAX7324 series (AEG+, AEG+T, ATG+, ATG+T) offers enhanced output current (20mA) and extended temperature range (-40°C ~ 125°C) in larger packages (24-QSOP or 24-TQFN). These parts are suitable for applications requiring higher drive capability or wider temperature operation, with the trade-off of increased package size and pin count.

All substitute parts maintain ROHS3 compliance and REACH unaffected status consistent with the original part.

Frequently Asked Questions (FAQ)

Q: Can PCAL6408ABSHP directly replace PCAL9554CBS,128 without PCB modification?

A: Yes. PCAL6408ABSHP maintains identical package geometry (16-HVQFN 3x3), pinout, and electrical specifications. Direct PCB substitution is possible without layout changes.

Q: What is the primary difference between NXP and Texas Instruments I/O expander options?

A: Both manufacturers provide 8-channel I/O expanders with 400 kHz I2C operation. NXP PCAL6408ABSHP offers direct package equivalence. Texas Instruments TCA6408 series provides alternative packages (16-TSSOP, 16-UQFN) with higher inventory availability. Selection depends on PCB layout constraints and supply chain requirements.

Q: Are MAX7324 parts compatible with PCAL9554CBS,128 designs?

A: MAX7324 parts provide functional I/O expansion at 400 kHz I2C with interrupt output. However, they use larger packages (24-QSOP or 24-TQFN) requiring PCB redesign. MAX7324 offers enhanced output current (20mA vs. 10mA/25mA) and extended temperature range (-40°C ~ 125°C vs. -40°C ~ 85°C). Selection requires PCB layout compatibility assessment.

Q: What is the impact of TCA6408AQPWRQ1 reduced supply voltage range (1.65V ~ 3.6V)?

A: TCA6408AQPWRQ1 operates at maximum 3.6V, compared to 5.5V for the original part. This part is suitable only for 3.3V or lower supply systems. Applications requiring 5V operation must use alternative parts with 1.65V ~ 5.5V range.

Q: Which substitute part offers the highest inventory availability?

A: TCA6408APWR from Texas Instruments provides the highest inventory (58400 pcs), followed by TCA6408ARSVR (35300 pcs). Both maintain full electrical compatibility with the original PCAL9554CBS,128.

Q: Do all substitute parts support SMBus protocol?

A: No. PCAL6408ABSHP and TCA6408 series (APWR, AQPWRQ1, ARSVR) support both I2C and SMBus. TCA9534 and MAX7324 series support I2C only. Applications requiring SMBus must use PCAL6408ABSHP or TCA6408 variants.

Q: What packaging options are available for space-constrained designs?

A: TCA6408ARSVR offers the smallest footprint in 16-UQFN (2.6x1.8) package. For applications requiring larger packages, MAX7324ATG+ and MAX7324ATG+T use 24-TQFN (4x4) with exposed pad for thermal management.

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