25LC040AT-I/MS EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The 25LC040AT-I/MS is a 4Kbit Serial Peripheral Interface (SPI) EEPROM memory IC manufactured by Microchip Technology. This non-volatile memory device operates at 10 MHz clock frequency with a supply voltage range of 2.5V to 5.5V and is housed in an 8-MSOP surface mount package. The part is currently active in production status with RoHS3 compliance and REACH unaffected classification.

Substitute parts are identified when equivalent memory capacity, interface protocol, and electrical specifications align with the main part's functional requirements. The 25LC040AT-I/MS operates within defined parameters that establish compatibility boundaries for alternative components.

Key Parameters

Parameter	Value
Memory Type	Non-Volatile EEPROM
Memory Size	4Kbit
Memory Organization	512 x 8
Memory Interface	SPI
Clock Frequency	10 MHz
Write Cycle Time	5ms
Supply Voltage Range	2.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Mounting Type	Surface Mount
Package Type	8-MSOP (0.118", 3.00mm Width)
RoHS Status	ROHS3 Compliant
MSL Rating	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the 25LC040AT-I/MS are identified based on the following critical parameters:

Memory Capacity & Organization: All substitute parts maintain 4Kbit capacity with 512 x 8 organization, ensuring functional equivalence in data storage.

Interface Protocol: SPI interface is mandatory for all substitutes, maintaining software and hardware compatibility with existing circuit designs.

Supply Voltage Compatibility: The main part operates at 2.5V ~ 5.5V. Substitute parts with wider voltage ranges (1.7V ~ 5.5V or 1.8V ~ 5.5V) are compatible as they encompass the original specification. Parts with identical or overlapping voltage ranges are functionally equivalent.

Clock Frequency: The 10 MHz specification of the main part establishes a minimum performance threshold. Substitute parts operating at 10 MHz or higher (20 MHz) maintain backward compatibility.

Write Cycle Time: All identified substitutes maintain 5ms write cycle time, with one exception (M95040-DRDW8TP/K at 4ms), which represents improved performance.

Package Considerations: The main part uses 8-MSOP packaging (0.118", 3.00mm width). Substitute parts in 8-TSSOP packaging (0.173", 4.40mm width) represent different physical footprints and require PCB layout modifications.

Temperature Range: The main part operates -40°C ~ 85°C. Substitutes with identical or extended temperature ranges maintain compatibility.

Compliance & Certifications: RoHS3 compliance and REACH unaffected status are maintained across all substitutes. Automotive-grade parts (AEC-Q100 qualified) represent enhanced reliability options.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Clock Frequency	Supply Voltage	Operating Temp	Package Type	Write Cycle Time	Product Status	Automotive Grade
25LC040AT-I/MS	Microchip Technology	4Kbit	10 MHz	2.5V ~ 5.5V	-40°C ~ 85°C	8-MSOP	5ms	Active	No
AT25040B-XHL-B	Microchip Technology	4Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	5ms	Active	No
AT25040B-XHL-T	Microchip Technology	4Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	5ms	Active	No
CAT25040YI-G	onsemi	4Kbit	Not Specified	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	5ms	Obsolete	No
CAT25040YI-GT3	onsemi	4Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	5ms	Active	No
CAV25040YE-GT3	onsemi	4Kbit	10 MHz	2.5V ~ 5.5V	-40°C ~ 125°C	8-TSSOP	5ms	Active	Yes
M95040-DFDW6TP	STMicroelectronics	4Kbit	20 MHz	1.7V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	5ms	Active	No
M95040-DRDW8TP/K	STMicroelectronics	4Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 105°C	8-TSSOP	4ms	Active	Yes
M95040-RDW6TP	STMicroelectronics	4Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	5ms	Active	No
M95040-WDW6TP	STMicroelectronics	4Kbit	20 MHz	2.5V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	5ms	Active	No

Engineering Selection Recommendations

Direct Package Compatibility (8-MSOP): No substitute parts are available in the original 8-MSOP package format. All identified substitutes use 8-TSSOP packaging, requiring PCB redesign for physical footprint accommodation.

Voltage Range Alignment: The main part specifies 2.5V ~ 5.5V supply voltage. Substitutes with lower minimum voltage thresholds (1.7V, 1.8V) provide extended low-voltage operation capability while maintaining upper voltage compatibility. M95040-WDW6TP maintains identical voltage specification (2.5V ~ 5.5V) to the main part.

Clock Frequency Considerations: The main part operates at 10 MHz. Substitutes rated at 20 MHz provide doubled clock frequency capability, enabling faster data transfer rates while maintaining backward compatibility with 10 MHz operation. CAV25040YE-GT3 matches the 10 MHz specification exactly.

Temperature Range: The main part operates -40°C ~ 85°C. M95040-DRDW8TP/K extends the upper temperature limit to 105°C, suitable for elevated ambient applications. CAV25040YE-GT3 extends to 125°C for automotive thermal environments.

Automotive Qualification: CAV25040YE-GT3 and M95040-DRDW8TP/K carry AEC-Q100 qualification, indicating enhanced reliability screening and suitability for automotive applications.

Product Status: CAT25040YI-G is marked obsolete and should not be selected for new designs. All other substitutes maintain active production status.

Compliance Verification: All substitute parts maintain RoHS3 compliance and REACH unaffected status, matching the main part's regulatory classification.

Frequently Asked Questions (FAQ)

Q: Can I use an 8-TSSOP packaged substitute in place of the 8-MSOP main part without PCB modification?

A: No. The 8-MSOP package (0.118", 3.00mm width) and 8-TSSOP package (0.173", 4.40mm width) have different physical dimensions and pin spacing. PCB layout and footprint modifications are required for any 8-TSSOP substitute.

Q: Are 20 MHz clock frequency substitutes backward compatible with 10 MHz circuit designs?

A: Yes. Substitutes rated at 20 MHz operate at higher maximum clock frequencies but are compatible with circuits designed for 10 MHz operation. The device will function correctly when clocked at 10 MHz or lower.

Q: What is the significance of the write cycle time difference in M95040-DRDW8TP/K (4ms vs. 5ms)?

A: The 4ms write cycle time represents improved performance compared to the 5ms specification of the main part. This faster write cycle is backward compatible with designs expecting 5ms write times, as the actual write operation completes sooner than anticipated.

Q: Which substitute offers the closest electrical specification match to the 25LC040AT-I/MS?

A: CAV25040YE-GT3 matches the main part's 10 MHz clock frequency and 2.5V ~ 5.5V supply voltage range. However, it uses 8-TSSOP packaging instead of 8-MSOP and extends the operating temperature to -40°C ~ 125°C with AEC-Q100 automotive qualification.

Q: Can I substitute a part with 1.8V minimum voltage for a design requiring 2.5V minimum operation?

A: No. If your circuit design requires 2.5V minimum supply voltage operation, you must select substitutes with 2.5V minimum specification: M95040-WDW6TP or CAV25040YE-GT3. Parts with 1.8V or 1.7V minimums may not operate reliably at 2.5V if the design margin is critical.

Q: Why is CAT25040YI-G listed as a substitute if it is obsolete?

A: CAT25040YI-G is included in the cross-reference data provided but carries obsolete product status. It should not be selected for new designs. Active alternatives from onsemi include CAT25040YI-GT3 and CAV25040YE-GT3.

Q: What does "DiGi-Electronics Programmable: Verified" indicate?

A: This designation indicates that the part has been verified for programming compatibility within DiGi-Electronics' supply chain and testing protocols. The main part (25LC040AT-I/MS) and M95040-WDW6TP carry this verification status.

Q: Are all substitutes RoHS3 compliant?

A: Yes. All identified substitute parts maintain RoHS3 compliance and REACH unaffected status, matching the regulatory classification of the main part.

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