25LC128X-E/ST EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The 25LC128X-E/ST is a 128Kbit Serial Peripheral Interface (SPI) EEPROM memory IC manufactured by Microchip Technology, packaged in 8-TSSOP surface mount configuration. This non-volatile memory device operates at 10 MHz clock frequency with a 5ms write cycle time and supports supply voltages from 2.5V to 5.5V across an operating temperature range of -40°C to 125°C. The part is currently in active product status with ROHS3 compliance and unlimited moisture sensitivity level (MSL 1).

Substitute parts are necessary when the primary part becomes unavailable, when alternative performance specifications are required for specific applications, or when design flexibility demands components from different manufacturers with equivalent electrical and mechanical characteristics.

Key Parameters

Parameter	Value
Memory Size	128Kbit
Memory Organization	16K x 8
Memory Interface	SPI
Clock Frequency	10 MHz
Write Cycle Time	5ms
Voltage Supply Range	2.5V ~ 5.5V
Operating Temperature	-40°C ~ 125°C
Package Type	8-TSSOP
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution compatibility for the 25LC128X-E/ST is determined by the following critical parameters:

Core Electrical Requirements:

Memory capacity: 128Kbit (16K x 8 organization)
Interface protocol: SPI
Supply voltage range: Must encompass or be compatible with 2.5V ~ 5.5V
Operating temperature range: Must support -40°C ~ 125°C minimum
Write cycle time: 5ms or faster

Mechanical Requirements:

Package type: 8-TSSOP or equivalent 8-pin small outline surface mount package
Pin configuration: Compatible with 8-TSSOP pinout

Compliance Requirements:

RoHS3 compliance mandatory
MSL rating: 1 (Unlimited)

Substitute parts are grouped into two categories:

Category A - Direct Equivalents (10 MHz Operation): Parts operating at 10 MHz clock frequency with identical voltage and temperature specifications. These provide drop-in replacement capability with no performance trade-offs.

Category B - Enhanced Performance Substitutes (20 MHz Operation): Parts operating at 20 MHz clock frequency with modified voltage or temperature specifications. These offer higher performance but require verification of application compatibility with altered electrical parameters.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Clock Frequency	Write Cycle Time	Voltage Supply	Operating Temperature	Package	Product Status
25LC128X-E/ST	Microchip Technology	128Kbit	10 MHz	5ms	2.5V ~ 5.5V	-40°C ~ 125°C	8-TSSOP	Active
25LC128-E/ST	Microchip Technology	128Kbit	10 MHz	5ms	2.5V ~ 5.5V	-40°C ~ 125°C	8-TSSOP	Active
AT25128B-XHL-B	Microchip Technology	128Kbit	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	Active
AT25128B-XHL-T	Microchip Technology	128Kbit	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	Active
BR25S128FV-WE2	ROHM Semiconductor	128Kbit	20 MHz	5ms	1.7V ~ 5.5V	-40°C ~ 85°C	8-LSSOP	Not For New Designs
CAT25128YI-G	onsemi	128Kbit	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	Obsolete
CAT25128YI-GT3	onsemi	128Kbit	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	Active
CAV25128YE-GT3	onsemi	128Kbit	10 MHz	5ms	2.5V ~ 5.5V	-40°C ~ 125°C	8-TSSOP	Active
M95128-DRDW3TP/K	STMicroelectronics	128Kbit	20 MHz	4ms	1.8V ~ 5.5V	-40°C ~ 125°C	8-TSSOP	Active
M95128-DWDW4TP/K	STMicroelectronics	128Kbit	20 MHz	4ms	2.5V ~ 5.5V	-40°C ~ 145°C	8-TSSOP	Active
M95128-RDW6TP	STMicroelectronics	128Kbit	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	Active

Engineering Selection Recommendations

Recommended Primary Substitute: 25LC128-E/ST (Microchip Technology) — Identical electrical and mechanical specifications to the 25LC128X-E/ST with active product status and equivalent inventory availability. This part provides direct substitution without design modification.

Recommended Secondary Substitutes for Enhanced Performance Applications:

M95128-DWDW4TP/K (STMicroelectronics) — Offers 20 MHz clock frequency with extended operating temperature range (-40°C ~ 145°C) and faster write cycle time (4ms). Maintains 2.5V ~ 5.5V supply voltage compatibility. Suitable for high-temperature automotive and industrial applications requiring extended thermal performance.

M95128-DRDW3TP/K (STMicroelectronics) — Provides 20 MHz operation with full -40°C ~ 125°C temperature range coverage. Includes AEC-Q100 automotive qualification. Requires verification of 1.8V minimum supply voltage compatibility if 2.5V minimum operation is mandatory.

CAV25128YE-GT3 (onsemi) — Maintains 10 MHz operation with identical voltage (2.5V ~ 5.5V) and temperature (-40°C ~ 125°C) specifications. Includes AEC-Q100 automotive qualification and Digi-Electronics verification. Suitable for automotive applications requiring equivalent performance characteristics.

Parts Not Recommended for New Designs:

BR25S128FV-WE2 (ROHM Semiconductor) — Marked "Not For New Designs" status. Package variant (8-LSSOP) differs from standard 8-TSSOP, requiring PCB layout modification.

CAT25128YI-G (onsemi) — Obsolete product status. Avoid for new designs despite active inventory.

Frequently Asked Questions (FAQ)

Q: Can I use a 20 MHz substitute part in place of the 10 MHz 25LC128X-E/ST?

A: Yes, provided the application does not require the extended temperature range (-40°C ~ 125°C) of the original part. Most 20 MHz substitutes operate to -40°C ~ 85°C only. Verify your application's maximum operating temperature requirement before substitution. Higher clock frequency does not create compatibility issues in SPI interface applications.

Q: What is the difference between 8-TSSOP and 8-LSSOP packages?

A: Both are 8-pin small outline surface mount packages with identical pin pitch and electrical compatibility. The primary difference is package width: 8-TSSOP measures 0.173" (4.40mm) width, while 8-LSSOP is a variant designation. Verify PCB footprint compatibility before selecting BR25S128FV-WE2 or other LSSOP variants.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All parts listed in this reference maintain ROHS3 compliance and MSL 1 (Unlimited) moisture sensitivity rating, matching the original 25LC128X-E/ST specifications.

Q: Which substitute offers the best write performance?

A: M95128-DRDW3TP/K and M95128-DWDW4TP/K both feature 4ms write cycle time, compared to 5ms for the original part. This represents a 20% performance improvement. Both parts maintain SPI interface compatibility and 128Kbit capacity.

Q: Can I substitute a part with lower voltage minimum (1.8V) if my application uses 2.5V supply?

A: Yes. Parts rated 1.8V ~ 5.5V operate correctly at 2.5V supply voltage. The lower minimum rating provides additional design flexibility without affecting operation at higher voltages. Verify that your application does not require guaranteed operation below 1.8V before selecting these parts.

Q: What does AEC-Q100 qualification mean?

A: AEC-Q100 is an automotive industry qualification standard for integrated circuits. Parts bearing this qualification (M95128-DRDW3TP/K, M95128-DWDW4TP/K, CAV25128YE-GT3) have undergone enhanced reliability testing and are approved for automotive applications. Non-qualified parts are suitable for industrial and consumer applications.

Q: Is the 25LC128-E/ST truly identical to 25LC128X-E/ST?

A: Both parts share identical electrical specifications, memory organization, package type, and operating parameters. The primary difference is base product number designation (25LC128 vs. 25LC128X). Verify part number compatibility with your supplier before ordering.

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