24AA256T-E/ST EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The 24AA256T-E/ST is a 256Kbit I2C EEPROM memory IC manufactured by Microchip Technology, packaged in 8-TSSOP surface mount configuration. This non-volatile memory device operates across a wide voltage range (1.7V to 5.5V) and temperature range (-40°C to 125°C), making it suitable for industrial and consumer applications requiring persistent data storage. The part is currently active in production with ROHS3 compliance and unlimited moisture sensitivity rating. Equivalent and substitute parts are identified based on matching core electrical and mechanical specifications that ensure functional interchangeability in circuit designs.

Key Parameters

Parameter	24AA256T-E/ST
Memory Size	256Kbit
Memory Organization	32K x 8
Memory Interface	I2C
Clock Frequency	400 kHz
Access Time	900 ns
Write Cycle Time	5ms
Voltage Supply Range	1.7V ~ 5.5V
Operating Temperature	-40°C ~ 125°C
Package Type	8-TSSOP (0.173", 4.40mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the 24AA256T-E/ST are qualified based on the following critical parameters that determine functional interchangeability:

Core Electrical Compatibility:

Memory capacity: 256Kbit (32K x 8 organization)
Interface protocol: I2C
Write cycle time: 5ms
Package type: 8-TSSOP surface mount

Voltage and Temperature Considerations: Substitutes must operate within overlapping voltage ranges. The 24AA256T-E/ST operates from 1.7V to 5.5V. Substitute parts with minimum voltage specifications of 1.6V or 1.8V remain compatible with standard 3.3V and 5V supply designs. Operating temperature ranges may vary; substitutes rated to -40°C to 85°C cover the majority of industrial applications, while the original part extends to 125°C for high-temperature environments.

Clock Frequency: The 24AA256T-E/ST operates at 400 kHz I2C clock frequency. Substitute parts rated at 400 kHz or higher (1 MHz) are functionally compatible, as higher-speed devices operate correctly at lower clock rates.

Access Time: The 24AA256T-E/ST specifies 900 ns access time. Substitute parts with equal or faster access times (450 ns) maintain or improve performance characteristics.

Parameter Comparison

Parameter	24AA256T-E/ST (Microchip)	BR24G256FVT-3GE2 (Rohm)	BR24T256FVT-WE2 (Rohm)	M24256-BFDW6TP (STMicro)	M24256-BRDW6TP (STMicro)	M24256-DRDW8TP/K (STMicro)
Memory Size	256Kbit	256Kbit	256Kbit	256Kbit	256Kbit	256Kbit
Memory Organization	32K x 8	32K x 8	32K x 8	32K x 8	32K x 8	32K x 8
Memory Interface	I2C	I2C	I2C	I2C	I2C	I2C
Clock Frequency	400 kHz	400 kHz	400 kHz	1 MHz	1 MHz	1 MHz
Access Time	900 ns	Not specified	Not specified	450 ns	450 ns	450 ns
Write Cycle Time	5ms	5ms	5ms	5ms	5ms	5ms
Voltage Supply Range	1.7V ~ 5.5V	1.6V ~ 5.5V	1.6V ~ 5.5V	1.7V ~ 5.5V	1.8V ~ 5.5V	1.8V ~ 5.5V
Operating Temperature	-40°C ~ 125°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 105°C
Package Type	8-TSSOP	8-TSSOP-B	8-TSSOP-B	8-TSSOP	8-TSSOP	8-TSSOP
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Grade	Commercial	Commercial	Commercial	Commercial	Commercial	Automotive (AEC-Q100)

Engineering Selection Recommendations

Rohm Semiconductor BR24G256FVT-3GE2 and BR24T256FVT-WE2: Both Rohm parts maintain full I2C protocol compatibility and 400 kHz clock frequency matching. Operating temperature range extends to 85°C, suitable for standard industrial applications. Voltage supply range of 1.6V to 5.5V provides broader low-voltage compatibility. Package designation 8-TSSOP-B indicates minor physical variations within the TSSOP footprint family; PCB layout verification is recommended for high-density designs.

STMicroelectronics M24256-BFDW6TP and M24256-BRDW6TP: Both STMicro parts operate at 1 MHz I2C clock frequency with 450 ns access time, providing performance headroom above the original specification. M24256-BFDW6TP supports 1.7V minimum supply voltage, matching the original part. M24256-BRDW6TP specifies 1.8V minimum, suitable for 3.3V and 5V systems. Both are rated to 85°C operating temperature. These parts are suitable for designs requiring faster I2C communication or improved access time performance.

STMicroelectronics M24256-DRDW8TP/K: This variant extends operating temperature to 105°C and carries AEC-Q100 automotive qualification. Voltage supply range is 1.8V to 5.5V. This part is specified for automotive-grade applications requiring enhanced temperature performance and qualification documentation. All other electrical parameters align with the M24256 family specifications.

Compliance and Certification: All substitute parts maintain ROHS3 compliance and unlimited moisture sensitivity rating (MSL 1), matching the original part's environmental qualification. REACH status is unaffected across all variants.

Frequently Asked Questions (FAQ)

Q: Can I substitute the 24AA256T-E/ST with a Rohm BR24G256FVT-3GE2 in a design operating at 125°C? A: No. The BR24G256FVT-3GE2 is rated to 85°C maximum operating temperature. For applications requiring 125°C operation, the original 24AA256T-E/ST or equivalent parts with matching temperature specifications must be used. The M24256-DRDW8TP/K extends to 105°C but does not reach 125°C.

Q: What is the difference between 8-TSSOP and 8-TSSOP-B packaging? A: Both designations refer to 8-pin thin shrink small outline packages with 0.173" width and 4.40mm body width. The "-B" suffix indicates minor physical or lead configuration variations within the TSSOP family. Footprint compatibility should be verified with the PCB design and component datasheet before production implementation.

Q: Are the STMicroelectronics M24256 parts with 1 MHz clock frequency backward compatible with 400 kHz I2C bus designs? A: Yes. I2C devices operate at the bus clock frequency determined by the master controller. A 1 MHz-rated device functions correctly on a 400 kHz I2C bus. The higher frequency rating indicates the device's maximum supported clock speed, not its operating requirement.

Q: Which substitute part should I select for high-temperature automotive applications? A: The M24256-DRDW8TP/K is specified for automotive applications with AEC-Q100 qualification and operates to 105°C. This part is suitable for automotive-grade designs requiring temperature performance above standard commercial ratings.

Q: Can I use substitute parts with lower minimum voltage specifications (1.6V) in a 5V system? A: Yes. Parts rated 1.6V to 5.5V are fully compatible with 5V supply designs. The lower minimum voltage specification indicates broader operational range and does not affect performance in standard 5V applications.

Q: What is the inventory status of substitute parts? A: Inventory levels vary by part number. M24256-BRDW6TP shows highest availability at 32,452 pieces. BR24G256FVT-3GE2 has 16,373 pieces available. Specific inventory should be confirmed with the component supplier for production requirements.

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