Equivalent & Substitute Parts for 25AA128XT-I/ST

Part Overview

The 25AA128XT-I/ST is a 128Kbit EEPROM memory IC manufactured by Microchip Technology, featuring SPI interface with 10 MHz clock frequency and 8-TSSOP surface mount packaging. This non-volatile memory device operates across a wide voltage range of 1.8V to 5.5V and supports industrial temperature ranges from -40°C to 85°C. The part is ROHS3 compliant and currently in active production status with 1149 units in stock.

Equivalent and substitute parts are necessary when the primary part becomes unavailable, when higher performance specifications are required, or when design flexibility demands alternative sourcing options from qualified manufacturers.

Key Parameters

Parameter	Value
Memory Size	128Kbit
Memory Organization	16K x 8
Memory Interface	SPI
Clock Frequency	10 MHz
Voltage Supply Range	1.8V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Write Cycle Time	5ms
Package Type	8-TSSOP
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the 25AA128XT-I/ST is determined by the following critical parameters:

Core Compatibility Requirements:

Memory Size: 128Kbit (fixed requirement)
Memory Organization: 16K x 8 (fixed requirement)
Memory Interface: SPI (fixed requirement)
Package Type: 8-TSSOP (fixed requirement)
Voltage Supply Range: 1.8V ~ 5.5V (minimum requirement)
Operating Temperature: -40°C minimum and 85°C maximum (minimum requirement)

Performance Enhancement Parameters (allow substitution with equal or superior specifications):

Clock Frequency: 10 MHz or higher
Write Cycle Time: 5ms or faster

All substitute parts listed meet or exceed the core compatibility requirements. Parts with higher clock frequencies (20 MHz) or faster write cycle times (4ms) provide performance enhancement without compromising functional compatibility.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Clock Frequency	Write Cycle Time	Voltage Supply	Operating Temperature	Package	Inventory
25AA128XT-I/ST	Microchip Technology	128Kbit	10 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	1149 Pcs
25AA128T-I/ST	Microchip Technology	128Kbit	10 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	2096 Pcs
AT25128B-XHL-T	Microchip Technology	128Kbit	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	7108 Pcs
CAT25128YI-GT3	onsemi	128Kbit	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	6804 Pcs
M95128-DRDW3TP/K	STMicroelectronics	128Kbit	20 MHz	4ms	1.8V ~ 5.5V	-40°C ~ 125°C	8-TSSOP	7448 Pcs
M95128-DRDW8TP/K	STMicroelectronics	128Kbit	20 MHz	4ms	1.8V ~ 5.5V	-40°C ~ 105°C	8-TSSOP	3200 Pcs
M95128-RDW6TP	STMicroelectronics	128Kbit	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	16114 Pcs

Engineering Selection Recommendations

Direct Equivalent (Same Specifications): The 25AA128T-I/ST from Microchip Technology is a direct equivalent with identical electrical and thermal specifications. This part differs only in packaging format (Cut Tape & Digi-Reel versus Tape & Reel) and carries verified DiGi-Electronics programmable status with higher inventory availability.

Performance-Enhanced Substitutes (Higher Clock Frequency): The AT25128B-XHL-T, CAT25128YI-GT3, M95128-DRDW3TP/K, M95128-DRDW8TP/K, and M95128-RDW6TP all feature 20 MHz clock frequency, providing double the performance headroom while maintaining full backward compatibility. These parts support faster data transfer rates without requiring design modifications.

Automotive-Grade Options: The M95128-DRDW3TP/K and M95128-DRDW8TP/K carry AEC-Q100 automotive qualification and extended temperature ratings (-40°C to 125°C and -40°C to 105°C respectively), suitable for applications requiring automotive-grade reliability. The M95128-DRDW3TP/K additionally features 4ms write cycle time.

Inventory Considerations: The M95128-RDW6TP offers the highest inventory level at 16114 units, followed by AT25128B-XHL-T at 7108 units, providing supply chain flexibility for high-volume applications.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with 20 MHz clock frequency in place of the 10 MHz 25AA128XT-I/ST? A: Yes. The 20 MHz parts (AT25128B-XHL-T, CAT25128YI-GT3, M95128 series) are fully compatible. Higher clock frequency is a performance enhancement that does not affect functional compatibility. Existing firmware and hardware interfaces will operate without modification.

Q: What is the difference between 25AA128XT-I/ST and 25AA128T-I/ST? A: Both parts are identical in electrical and thermal specifications. The primary difference is packaging format: 25AA128XT-I/ST is supplied in Tape & Reel format, while 25AA128T-I/ST is supplied in Cut Tape & Digi-Reel format. The 25AA128T-I/ST also carries verified DiGi-Electronics programmable status.

Q: Are the STMicroelectronics M95128 parts compatible with my existing design? A: Yes. All M95128 variants maintain the same 128Kbit capacity, 16K x 8 organization, SPI interface, 8-TSSOP package, and voltage supply range. The M95128-DRDW3TP/K and M95128-DRDW8TP/K feature extended temperature ratings suitable for automotive applications.

Q: What is the significance of the write cycle time difference between 5ms and 4ms? A: The 4ms write cycle time in M95128-DRDW3TP/K and M95128-DRDW8TP/K represents faster page write operations. This is a performance enhancement that does not affect compatibility. Applications requiring faster write operations benefit from this specification.

Q: Can I mix different manufacturers' parts in the same design? A: Yes. All listed parts meet identical core specifications for memory size, organization, interface, package, and voltage range. Cross-manufacturer substitution is supported within the same design, provided the application does not depend on manufacturer-specific features or timing characteristics beyond the specified parameters.

Q: Which substitute part should I select for maximum supply availability? A: The M95128-RDW6TP offers the highest inventory at 16114 units. For Microchip-only designs, the AT25128B-XHL-T provides 7108 units with performance enhancement to 20 MHz clock frequency.

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