TCA9555RTWR Equivalent & Substitute Parts

Part Overview

The TCA9555RTWR is a 16-bit I/O expander from Texas Instruments designed for I2C and SMBus communication at 400 kHz. It features push-pull output configuration with 10mA/25mA source/sink capability, power-on reset (POR), and interrupt output functionality. The device operates across a wide supply voltage range of 1.65V to 5.5V and temperature range of -40°C to 85°C in a 24-WQFN surface mount package.

The TCA9555RTWR maintains active product status with ROHS3 compliance and is widely available. Equivalent and substitute parts are identified based on matching core functional parameters: 16 I/O count, I2C/SMBus interface at 400 kHz clock frequency, push-pull or open-drain output types, and compatible package form factors.

Key Parameters

Parameter	TCA9555RTWR Specification
Manufacturer	Texas Instruments
Number of I/O	16
Interface	I2C, SMBus
Clock Frequency	400 kHz
Output Type	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	24-WQFN Exposed Pad
Product Status	Active
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	2 (1 Year)

Substitute Part Grouping Explanation

Substitution eligibility for the TCA9555RTWR is determined by the following core parameters:

Primary Matching Criteria:

16 I/O count
I2C or I2C/SMBus interface support
400 kHz clock frequency operation
Push-pull output capability (or open-drain where functionally compatible)
Surface mount package compatibility
Active or recently active product status
ROHS3 compliance

Secondary Compatibility Factors:

Supply voltage range (minimum 1.65V to 5.5V preferred; 2V to 5.5V acceptable)
Operating temperature range (-40°C to 85°C or wider)
Output current capability (10mA/25mA or higher)
Interrupt output presence
Power-on reset feature

Substitute parts are grouped into two categories: direct pin-compatible replacements in equivalent packages (24-WQFN/HWQFN/HVQFN variants) and functional equivalents in alternative packages (28-pin SOIC, SSOP, SPDIP) that require PCB layout modification but maintain electrical compatibility.

Parameter Comparison

Part Number	Manufacturer	I/O Count	Interface	Clock Frequency	Output Type	Current Source/Sink	Supply Voltage	Operating Temp	Package	Product Status
TCA9555RTWR	Texas Instruments	16	I2C, SMBus	400 kHz	Push-Pull	10mA, 25mA	1.65V ~ 5.5V	-40°C ~ 85°C	24-WQFN	Active
MAX7312ATG+	Analog Devices Inc./Maxim Integrated	16	I2C, SMBus	400 kHz	Push-Pull	31mA, 43mA	2V ~ 5.5V	-40°C ~ 125°C	24-TQFN	Active
MCP23016-I/SP	Microchip Technology	16	I2C	400 kHz	Push-Pull	25mA	2V ~ 5.5V	-40°C ~ 85°C	28-SPDIP	Active
MCP23016-I/SS	Microchip Technology	16	I2C	400 kHz	Push-Pull	25mA	2V ~ 5.5V	-40°C ~ 85°C	28-SSOP	Active
MCP23016T-I/SO	Microchip Technology	16	I2C	400 kHz	Push-Pull	25mA	2V ~ 5.5V	-40°C ~ 85°C	28-SOIC	Active
PCA9535AHF,128	NXP USA Inc.	16	I2C, SMBus	400 kHz	Push-Pull	10mA, 25mA	1.65V ~ 5.5V	-40°C ~ 85°C	24-HWQFN	Active
PCA9535CHF,118	NXP USA Inc.	16	I2C, SMBus	400 kHz	Open Drain	10mA, 25mA	2.3V ~ 5.5V	-40°C ~ 85°C	24-HWQFN	Active
PCA9555BS,118	NXP USA Inc.	16	I2C, SMBus	400 kHz	Push-Pull	10mA, 25mA	2.3V ~ 5.5V	-40°C ~ 85°C	24-HVQFN	Active
PCA9655EMTTXG	onsemi	16	I2C, SMBus	100 kHz	Push-Pull	42mA	1.65V ~ 5.5V	-55°C ~ 125°C	24-QFN	Obsolete

Engineering Selection Recommendations

Direct Substitutes (Pin-Compatible, 24-Pin QFN Variants):

PCA9535AHF,128 and PCA9555BS,118 from NXP USA Inc. are the closest functional equivalents to the TCA9555RTWR. Both maintain 16 I/O, I2C/SMBus 400 kHz operation, push-pull output, and 24-pin QFN package form factors. PCA9535AHF,128 matches the full supply voltage range (1.65V ~ 5.5V) and is recommended for applications requiring maximum voltage flexibility. PCA9555BS,118 operates from 2.3V ~ 5.5V and is suitable for standard 3.3V and 5V systems. Both devices are active products with ROHS3 compliance and unlimited moisture sensitivity rating.

MAX7312ATG+ from Analog Devices Inc./Maxim Integrated provides enhanced output current capability (31mA/43mA versus 10mA/25mA) and extended operating temperature range (-40°C ~ 125°C). This device is suitable for applications requiring higher drive capability or wider temperature operation. The 24-TQFN package is mechanically compatible with standard 24-pin QFN footprints.

Alternative Package Substitutes (28-Pin Variants):

MCP23016 series devices from Microchip Technology (MCP23016-I/SP in 28-SPDIP, MCP23016-I/SS in 28-SSOP, MCP23016T-I/SO in 28-SOIC) provide functional equivalence with 16 I/O, I2C 400 kHz operation, and push-pull output. These parts require PCB layout redesign due to different pin counts and package footprints. All MCP23016 variants are active products with ROHS3 compliance and operate from 2V ~ 5.5V across -40°C ~ 85°C temperature range.

Not Recommended:

PCA9655EMTTXG is marked as obsolete and operates at 100 kHz clock frequency, which does not meet the 400 kHz specification of the TCA9555RTWR. This part should not be selected for new designs.

PCA9535CHF,118 features open-drain output configuration rather than push-pull, which may require external pull-up resistors and is not directly compatible with push-pull applications.

Frequently Asked Questions (FAQ)

Q: Can PCA9535AHF,128 directly replace TCA9555RTWR without PCB modification?

A: Yes. Both devices use 24-pin QFN packages with compatible pinouts for I2C/SMBus 16-bit I/O expansion at 400 kHz. The PCA9535AHF,128 maintains identical supply voltage range (1.65V ~ 5.5V) and operating temperature (-40°C ~ 85°C). No PCB layout changes are required.

Q: What is the key difference between PCA9535AHF,128 and PCA9555BS,118?

A: Both are NXP 16-bit I2C/SMBus I/O expanders in 24-pin QFN packages at 400 kHz. The primary difference is supply voltage range: PCA9535AHF,128 operates from 1.65V ~ 5.5V, while PCA9555BS,118 operates from 2.3V ~ 5.5V. Select PCA9535AHF,128 for applications requiring operation below 2.3V.

Q: Why does MAX7312ATG+ have higher output current specifications?

A: MAX7312ATG+ is specified for 31mA/43mA source/sink current compared to 10mA/25mA for TCA9555RTWR. This higher capability allows direct driving of more demanding loads without intermediate buffering stages. The trade-off is slightly higher power consumption.

Q: Can MCP23016 series parts be used as drop-in replacements?

A: No. MCP23016 devices use 28-pin packages (SPDIP, SSOP, SOIC) versus the 24-pin QFN of TCA9555RTWR. Pin count and pinout differences require PCB redesign. However, they provide functional equivalence for I2C 16-bit I/O expansion at 400 kHz and are suitable for new board layouts.

Q: What is the significance of moisture sensitivity level differences?

A: TCA9555RTWR has MSL 2 (1 Year), while most substitutes have MSL 1 (Unlimited). MSL 1 indicates superior moisture resistance and longer shelf life without baking requirements. Substitutes with MSL 1 offer manufacturing advantages for inventory management and reduced handling constraints.

Q: Is PCA9535CHF,118 compatible with TCA9555RTWR applications?

A: PCA9535CHF,118 uses open-drain output instead of push-pull. Open-drain requires external pull-up resistors and is not directly compatible with push-pull applications. Use only if your circuit design explicitly supports open-drain I/O configuration.

Q: Why is PCA9655EMTTXG listed as not recommended?

A: PCA9655EMTTXG is marked as obsolete and operates at 100 kHz clock frequency. The TCA9555RTWR specification requires 400 kHz operation. This part does not meet functional requirements and should not be selected for new designs.

Q: What compliance certifications apply to all recommended substitutes?

A: All active substitute parts listed maintain ROHS3 compliance and REACH Unaffected status, matching the TCA9555RTWR compliance profile. All are suitable for applications requiring these regulatory certifications.

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