25AA256T-E/ST EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The 25AA256T-E/ST is a 256Kbit Serial Peripheral Interface (SPI) EEPROM memory IC manufactured by Microchip Technology in an 8-TSSOP surface mount package. This non-volatile memory device operates across a wide supply voltage range of 1.8V to 5.5V and supports industrial temperature ranges from -40°C to 125°C. The part is currently in active production status with ROHS3 compliance and unlimited moisture sensitivity level rating. Substitute parts are necessary to address inventory availability, specific operational requirements such as extended clock frequency support, or automotive-grade qualification needs.

Key Parameters

Parameter	Value
Memory Size	256Kbit
Memory Organization	32K x 8
Memory Interface	SPI
Clock Frequency	10 MHz
Write Cycle Time	5ms
Voltage Supply Range	1.8V ~ 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

Substitution eligibility for the 25AA256T-E/ST is determined by the following critical parameters:

Core Compatibility Requirements:

Memory capacity: 256Kbit (32K x 8 organization)
Interface protocol: SPI
Package type: 8-TSSOP with identical 0.173" width and 4.40mm dimensions
Surface mount mounting type
Supply voltage range must encompass or exceed 1.8V ~ 5.5V
Operating temperature range must support -40°C minimum and 125°C maximum

Performance Considerations:

Clock frequency: 10 MHz minimum (higher frequencies are acceptable)
Write cycle time: 5ms or faster
RoHS3 compliance required

All substitute parts listed maintain identical memory capacity, organization, SPI interface, and 8-TSSOP package specifications. Variations exist in clock frequency capability, supply voltage floor, operating temperature ceiling, and automotive qualification status.

Parameter Comparison

Parameter	25AA256T-E/ST	AT25256B-XHL-B	CAV25256YE-GT3	M95256-DFDW6TP	M95256-DRDW3TP/K
Manufacturer	Microchip Technology	Microchip Technology	onsemi	STMicroelectronics	STMicroelectronics
Memory Size	256Kbit	256Kbit	256Kbit	256Kbit	256Kbit
Memory Organization	32K x 8	32K x 8	32K x 8	32K x 8	32K x 8
Memory Interface	SPI	SPI	SPI	SPI	SPI
Clock Frequency	10 MHz	20 MHz	10 MHz	20 MHz	20 MHz
Write Cycle Time	5ms	5ms	5ms	5ms	4ms
Voltage Supply Range	1.8V ~ 5.5V	1.8V ~ 5.5V	2.5V ~ 5.5V	1.7V ~ 5.5V	1.8V ~ 5.5V
Operating Temperature	-40°C ~ 125°C	-40°C ~ 85°C	-40°C ~ 125°C	-40°C ~ 85°C	-40°C ~ 125°C
Package Type	8-TSSOP	8-TSSOP	8-TSSOP	8-TSSOP	8-TSSOP
Automotive Grade	No	No	Yes (AEC-Q100)	No	Yes (AEC-Q100)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

AT25256B-XHL-B (Microchip Technology): Direct manufacturer alternative with identical supply voltage range and RoHS3 compliance. Operates at 20 MHz clock frequency, doubling the performance of the primary part. Operating temperature ceiling is reduced to 85°C, making this suitable for applications not requiring the full 125°C upper limit. Inventory availability is 2,159 units.

CAV25256YE-GT3 (onsemi): Maintains the full -40°C to 125°C operating temperature range and 10 MHz clock frequency matching the primary part. Includes AEC-Q100 automotive qualification, suitable for automotive applications. Supply voltage floor is 2.5V, which restricts use in systems requiring 1.8V operation. Inventory availability is 3,301 units.

M95256-DFDW6TP (STMicroelectronics): Offers 20 MHz clock frequency with supply voltage range of 1.7V to 5.5V. Operating temperature is limited to 85°C. RoHS3 compliant. Inventory availability is 2,863 units.

M95256-DRDW3TP/K (STMicroelectronics): Provides 20 MHz clock frequency with 4ms write cycle time (faster than the primary part's 5ms). Maintains full -40°C to 125°C operating temperature range and 1.8V to 5.5V supply voltage compatibility. Includes AEC-Q100 automotive qualification. RoHS3 compliant. Inventory availability is 2,100 units.

Frequently Asked Questions (FAQ)

Q: Can AT25256B-XHL-B replace 25AA256T-E/ST in all applications?

A: AT25256B-XHL-B is compatible for applications operating within -40°C to 85°C temperature range. If your system requires operation above 85°C, this substitute is not suitable. The 20 MHz clock frequency is a performance enhancement and does not create compatibility issues.

Q: What is the key difference between CAV25256YE-GT3 and other substitutes?

A: CAV25256YE-GT3 is the only substitute with AEC-Q100 automotive qualification and maintains the full -40°C to 125°C operating temperature range. However, its minimum supply voltage is 2.5V, which excludes it from applications requiring 1.8V operation.

Q: Is M95256-DRDW3TP/K a direct replacement for 25AA256T-E/ST?

A: M95256-DRDW3TP/K meets all core compatibility requirements: 256Kbit capacity, SPI interface, 8-TSSOP package, -40°C to 125°C operating range, and 1.8V to 5.5V supply voltage. It offers enhanced performance with 20 MHz clock frequency and 4ms write cycle time. AEC-Q100 qualification is an additional feature for automotive applications.

Q: Does clock frequency affect pin compatibility?

A: No. All substitute parts maintain identical 8-TSSOP pinout and SPI protocol. Higher clock frequency ratings do not alter electrical pin assignments or signal timing requirements at lower frequencies.

Q: Which substitute is best for low-voltage applications below 2.0V?

A: For applications requiring operation below 2.0V, only 25AA256T-E/ST (1.8V minimum), AT25256B-XHL-B (1.8V minimum), M95256-DFDW6TP (1.7V minimum), and M95256-DRDW3TP/K (1.8V minimum) are suitable. CAV25256YE-GT3 has a 2.5V minimum supply voltage and is not compatible.

Q: Are all substitutes RoHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance, matching the primary part's environmental and regulatory status.

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