25LC040AT-E/ST EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The 25LC040AT-E/ST 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-TSSOP surface mount package. The part is currently in active production status with ROHS3 compliance and unlimited moisture sensitivity rating (MSL 1). Substitute parts are necessary to address supply availability, packaging format requirements, or specific operational parameter needs in system designs.

Key Parameters

Parameter	Value
Memory Size	4Kbit
Memory Organization	512 x 8
Memory Interface	SPI
Clock Frequency	10 MHz
Write Cycle Time	5ms
Voltage Supply Range	2.5V ~ 5.5V
Operating Temperature Range	-40°C ~ 125°C
Package Type	8-TSSOP (0.173", 4.40mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
MSL Rating	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution compatibility for the 25LC040AT-E/ST is determined by the following critical parameters:

Primary Compatibility Criteria:

Memory capacity: 4Kbit
Memory organization: 512 x 8
Interface protocol: SPI
Package type: 8-TSSOP with 0.173" width and 4.40mm width dimensions
Supply voltage range: Must encompass or be compatible with 2.5V ~ 5.5V
Operating temperature range: Must support -40°C ~ 125°C minimum
Mounting type: Surface mount

Secondary Compatibility Factors:

Clock frequency: 10 MHz or higher
Write cycle time: 5ms or faster
Moisture sensitivity level: MSL 1 preferred for unlimited shelf life
RoHS compliance: ROHS3 required

Substitute parts are grouped into two categories: direct functional equivalents with identical or superior electrical specifications, and parts with extended operational capabilities (higher clock frequency, wider voltage range, automotive qualification) that maintain backward compatibility.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Clock Frequency (MHz)	Voltage Supply (V)	Operating Temp (°C)	Write Cycle (ms)	Package	MSL
25LC040AT-E/ST	Microchip Technology	4Kbit	10	2.5 ~ 5.5	-40 ~ 125	5	8-TSSOP	1
AT25040B-XHL-B	Microchip Technology	4Kbit	20	1.8 ~ 5.5	-40 ~ 85	5	8-TSSOP	3
AT25040B-XHL-T	Microchip Technology	4Kbit	20	1.8 ~ 5.5	-40 ~ 85	5	8-TSSOP	3
BR25H040FVT-2CE2	Rohm Semiconductor	4Kbit	10	2.5 ~ 5.5	-40 ~ 125	4	8-TSSOP-B	1
CAT25040YI-GT3	onsemi	4Kbit	20	1.8 ~ 5.5	-40 ~ 85	5	8-TSSOP	1
CAV25040YE-GT3	onsemi	4Kbit	10	2.5 ~ 5.5	-40 ~ 125	5	8-TSSOP	1
M95040-DFDW6TP	STMicroelectronics	4Kbit	20	1.7 ~ 5.5	-40 ~ 85	5	8-TSSOP	1
M95040-DRDW3TP/K	STMicroelectronics	4Kbit	20	1.8 ~ 5.5	-40 ~ 125	4	8-TSSOP	1
M95040-DRDW8TP/K	STMicroelectronics	4Kbit	20	1.8 ~ 5.5	-40 ~ 105	4	8-TSSOP	1
M95040-RDW6TP	STMicroelectronics	4Kbit	20	1.8 ~ 5.5	-40 ~ 85	5	8-TSSOP	1
M95040-WDW6TP	STMicroelectronics	4Kbit	20	2.5 ~ 5.5	-40 ~ 85	5	8-TSSOP	1

Engineering Selection Recommendations

Direct Equivalents (Identical Electrical Performance): BR25H040FVT-2CE2 and CAV25040YE-GT3 provide electrical parameter matching with the 25LC040AT-E/ST, maintaining 10 MHz clock frequency, 2.5V to 5.5V supply voltage range, and -40°C to 125°C operating temperature. Both parts carry AEC-Q100 automotive qualification and MSL 1 rating. BR25H040FVT-2CE2 offers faster write cycle time (4ms vs 5ms).

Enhanced Performance Substitutes (Higher Clock Frequency): AT25040B-XHL-T, CAT25040YI-GT3, M95040-DFDW6TP, M95040-DRDW3TP/K, M95040-DRDW8TP/K, M95040-RDW6TP, and M95040-WDW6TP operate at 20 MHz clock frequency, providing doubled data throughput capability while maintaining 4Kbit capacity and SPI interface. These parts are suitable for applications requiring higher speed operation. M95040-DRDW3TP/K and M95040-DRDW8TP/K include AEC-Q100 automotive qualification.

Packaging Considerations: AT25040B-XHL-B is supplied in Tube packaging, while AT25040B-XHL-T uses Tape & Reel format. M95040-DRDW3TP/K and M95040-RDW6TP are supplied in Cut Tape & Digi-Reel format. All other substitutes use standard Tape & Reel packaging.

Temperature Range Limitations: AT25040B-XHL-B and AT25040B-XHL-T operate to 85°C maximum, reducing the upper temperature capability compared to the 25LC040AT-E/ST. CAT25040YI-GT3, M95040-DFDW6TP, and M95040-RDW6TP also limit operation to 85°C. M95040-DRDW8TP/K extends to 105°C. Applications requiring full -40°C to 125°C range should select BR25H040FVT-2CE2, CAV25040YE-GT3, or M95040-DRDW3TP/K.

Voltage Supply Range: M95040-DFDW6TP supports 1.7V minimum supply voltage, the lowest among all substitutes. AT25040B-XHL-B, AT25040B-XHL-T, CAT25040YI-GT3, M95040-DRDW3TP/K, and M95040-DRDW8TP/K support 1.8V minimum. The original 25LC040AT-E/ST and M95040-WDW6TP require 2.5V minimum supply voltage.

Compliance and Certification: All parts maintain ROHS3 compliance and REACH unaffected status. BR25H040FVT-2CE2, CAV25040YE-GT3, M95040-DRDW3TP/K, and M95040-DRDW8TP/K carry AEC-Q100 automotive qualification for applications requiring automotive-grade components.

Frequently Asked Questions (FAQ)

Q: Can I use a 20 MHz substitute part in place of the 10 MHz 25LC040AT-E/ST?

A: Yes. Higher clock frequency parts (AT25040B-XHL-T, CAT25040YI-GT3, M95040 series) are backward compatible with 10 MHz system designs. The SPI interface allows operation at lower clock speeds than the part's maximum rating. System performance will not be degraded; data throughput capability will be enhanced.

Q: What is the difference between the Tape & Reel and Cut Tape & Digi-Reel packaging options?

A: Tape & Reel (TR) packaging is standard for high-volume automated assembly. Cut Tape & Digi-Reel format (CT) provides flexibility for lower-volume or mixed-component orders. Both formats contain identical components; packaging selection depends on procurement and assembly process requirements.

Q: Are the Microchip AT25040B parts suitable for -40°C to 125°C applications?

A: No. AT25040B-XHL-B and AT25040B-XHL-T limit operation to -40°C to 85°C maximum temperature. For full -40°C to 125°C range, select BR25H040FVT-2CE2, CAV25040YE-GT3, or M95040-DRDW3TP/K.

Q: What does MSL 1 versus MSL 3 mean for component storage?

A: MSL 1 (Moisture Sensitivity Level 1) indicates unlimited shelf life without moisture bake-out requirements. MSL 3 requires moisture bake-out after 168 hours of exposure to ambient humidity. The 25LC040AT-E/ST carries MSL 1; AT25040B parts carry MSL 3, requiring additional handling procedures.

Q: Which substitute parts have automotive qualification?

A: BR25H040FVT-2CE2, CAV25040YE-GT3, M95040-DRDW3TP/K, and M95040-DRDW8TP/K carry AEC-Q100 automotive qualification. These parts are suitable for automotive and industrial applications requiring qualified component status.

Q: Can I substitute a part with lower minimum supply voltage (1.7V or 1.8V) in a 2.5V system?

A: Yes. Parts with lower minimum voltage specifications (M95040-DFDW6TP at 1.7V, or AT25040B and M95040 variants at 1.8V) are fully compatible in systems operating at 2.5V or higher. The lower minimum rating provides additional design flexibility for future applications.

Q: What is the significance of the write cycle time difference between 4ms and 5ms?

A: Write cycle time specifies the duration required to complete a single page write operation. BR25H040FVT-2CE2 and M95040-DRDW3TP/K offer 4ms write cycles versus 5ms for the original part. This faster write performance is beneficial for applications requiring rapid data logging or frequent memory updates, but does not affect compatibility in standard applications.

Q: Are all substitute parts pin-compatible with the 25LC040AT-E/ST?

A: All listed substitutes use the 8-TSSOP package with identical pinout and 0.173" width (4.40mm). BR25H040FVT-2CE2 uses 8-TSSOP-B variant, which maintains identical pin configuration and spacing. All parts are directly pin-compatible for PCB assembly without layout modifications.

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