Equivalent & Substitute Parts for 25LC040X-I/ST

Part Overview

The 25LC040X-I/ST is a 4Kbit EEPROM memory IC manufactured by Microchip Technology, featuring SPI interface operation at 2 MHz with 8-TSSOP surface mount packaging. This device is classified as Active product status and is RoHS3 compliant. Substitute parts are necessary when the original part becomes unavailable, when higher clock frequency operation is required, or when alternative packaging formats are needed for specific manufacturing processes.

Key Parameters

Parameter	Value
Memory Size	4Kbit
Memory Organization	512 x 8
Memory Interface	SPI
Clock Frequency	2 MHz
Write Cycle Time	5ms
Voltage Supply Range	2.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°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 25LC040X-I/ST is determined by the following critical parameters:

Core Compatibility Requirements:

Memory Size: 4Kbit (fixed requirement)
Memory Organization: 512 x 8 (fixed requirement)
Memory Interface: SPI (fixed requirement)
Package Type: 8-TSSOP (fixed requirement)
Mounting Type: Surface Mount (fixed requirement)

Variable Parameters Allowing Substitution:

Clock Frequency: May be equal to or higher than 2 MHz
Write Cycle Time: May be equal to or lower than 5ms
Voltage Supply Range: Must encompass or be compatible with 2.5V ~ 5.5V
Operating Temperature: May extend beyond -40°C ~ 85°C
Packaging Format: Tube, Tape & Reel, or Cut Tape formats are interchangeable

Substitute parts are grouped by clock frequency capability, voltage supply specifications, and temperature rating, as these parameters define operational performance boundaries while maintaining functional equivalence.

Parameter Comparison

Part Number	Manufacturer	Clock Frequency	Write Cycle Time	Voltage Supply	Operating Temperature	Packaging	Product Status
25LC040X-I/ST	Microchip Technology	2 MHz	5ms	2.5V ~ 5.5V	-40°C ~ 85°C	Tube	Active
25LC040A-I/ST	Microchip Technology	10 MHz	5ms	2.5V ~ 5.5V	-40°C ~ 85°C	Tube	Active
25LC040AX-I/ST	Microchip Technology	10 MHz	5ms	2.5V ~ 5.5V	-40°C ~ 85°C	Tube	Active
AT25040B-XHL-B	Microchip Technology	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	Tube	Active
M95040-DFDW6TP	STMicroelectronics	20 MHz	5ms	1.7V ~ 5.5V	-40°C ~ 85°C	Tape & Reel	Active
M95040-DRDW3TP/K	STMicroelectronics	20 MHz	4ms	1.8V ~ 5.5V	-40°C ~ 125°C	Cut Tape & Digi-Reel	Active
M95040-DRDW8TP/K	STMicroelectronics	20 MHz	4ms	1.8V ~ 5.5V	-40°C ~ 105°C	Tape & Reel	Active
M95040-RDW6TP	STMicroelectronics	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	Cut Tape & Digi-Reel	Active
M95040-WDW6TP	STMicroelectronics	20 MHz	5ms	2.5V ~ 5.5V	-40°C ~ 85°C	Tape & Reel	Active
R1EX25004ATA00I#S0	Renesas Electronics Corporation	5 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	Tape & Reel	Active

Engineering Selection Recommendations

All listed substitute parts maintain Active product status and RoHS3 compliance, ensuring long-term availability and regulatory conformance. Selection among substitutes should be based on the following criteria:

Direct Microchip Technology Substitutes (25LC040A-I/ST, 25LC040AX-I/ST): These parts offer higher clock frequency operation (10 MHz) while maintaining identical voltage supply range (2.5V ~ 5.5V) and temperature rating (-40°C ~ 85°C). Both are verified as programmable through DiGi-Electronics.

Higher Performance Microchip Option (AT25040B-XHL-B): Provides 20 MHz clock frequency with extended voltage supply range (1.8V ~ 5.5V). Moisture sensitivity level is MSL 3 (168 Hours), compared to MSL 1 for the original part.

STMicroelectronics M95040 Series: Offers 20 MHz operation with multiple packaging options. M95040-DRDW3TP/K and M95040-DRDW8TP/K include automotive qualification (AEC-Q100) with extended temperature ratings (-40°C ~ 125°C and -40°C ~ 105°C respectively) and reduced write cycle time (4ms). M95040-WDW6TP maintains the original voltage supply range (2.5V ~ 5.5V).

Renesas Electronics Option (R1EX25004ATA00I#S0): Provides 5 MHz operation with extended voltage supply range (1.8V ~ 5.5V) in Tape & Reel packaging.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with higher clock frequency than the original 25LC040X-I/ST?

A: Yes. Higher clock frequency operation is backward compatible. Parts rated at 10 MHz or 20 MHz can operate in applications designed for 2 MHz operation. The system clock speed will determine actual operating frequency.

Q: What is the difference between the Microchip 25LC040A-I/ST and 25LC040AX-I/ST?

A: Both parts are functionally equivalent with 10 MHz clock frequency, identical voltage supply range (2.5V ~ 5.5V), and matching temperature rating (-40°C ~ 85°C). Both are verified as programmable. Selection may be based on inventory availability or specific design requirements.

Q: Are STMicroelectronics M95040 parts compatible with the original 25LC040X-I/ST?

A: Yes, all M95040 variants maintain the same 4Kbit memory size, 512 x 8 organization, SPI interface, and 8-TSSOP package. Differences exist in clock frequency (20 MHz), voltage supply range (1.7V ~ 5.5V or 1.8V ~ 5.5V), write cycle time (4ms or 5ms), and packaging format (Tape & Reel or Cut Tape & Digi-Reel).

Q: What does MSL (Moisture Sensitivity Level) mean for component selection?

A: MSL indicates moisture sensitivity during storage and handling. MSL 1 (Unlimited) allows indefinite shelf life under controlled conditions. MSL 3 (168 Hours) requires baking before reflow if the part has been exposed to moisture for extended periods. The original 25LC040X-I/ST has MSL 1; AT25040B-XHL-B has MSL 3.

Q: Can I substitute the Tube packaging format with Tape & Reel?

A: Yes. Packaging format (Tube, Tape & Reel, Cut Tape & Digi-Reel) does not affect electrical or mechanical compatibility. Selection depends on manufacturing process requirements and handling procedures.

Q: Which substitute offers the best performance improvement?

A: M95040-DRDW3TP/K and M95040-DRDW8TP/K provide the highest clock frequency (20 MHz), fastest write cycle time (4ms), and extended temperature rating (-40°C ~ 125°C and -40°C ~ 105°C respectively). These parts include automotive qualification (AEC-Q100).

Q: Is the voltage supply range difference significant?

A: The original 25LC040X-I/ST operates at 2.5V ~ 5.5V. Substitutes with extended ranges (1.7V ~ 5.5V or 1.8V ~ 5.5V) provide greater flexibility for low-voltage applications. If your design operates above 2.5V, all substitutes are compatible.

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