25AA040AX-I/ST EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The 25AA040AX-I/ST is a 4Kbit Serial Peripheral Interface (SPI) EEPROM memory IC manufactured by Microchip Technology in 8-TSSOP surface mount packaging. This non-volatile memory device operates at 10 MHz clock frequency with a supply voltage range of 1.8V to 5.5V and is rated for industrial temperature range (-40°C to 85°C). The device is ROHS3 compliant and currently in active product status with 1500 units in stock.

Equivalent and substitute parts are necessary when the original part number becomes unavailable, when alternative packaging formats are required for manufacturing processes, or when enhanced performance specifications (such as higher clock frequency or automotive qualification) are beneficial for system requirements.

Key Parameters

Parameter	Value
Memory Size	4Kbit
Memory Organization	512 x 8
Memory Interface	SPI
Clock Frequency	10 MHz
Supply Voltage Range	1.8V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Package / Case	8-TSSOP (0.173", 4.40mm Width)
Write Cycle Time	5ms
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution compatibility for the 25AA040AX-I/ST is determined by the following critical parameters:

Mandatory Compatibility Parameters:

Memory Size: 4Kbit (512 x 8 organization)
Memory Interface: SPI
Package / Case: 8-TSSOP (0.173", 4.40mm Width)
Supply Voltage Range: Must encompass or match 1.8V ~ 5.5V
Operating Temperature: Must support -40°C ~ 85°C minimum

Performance Enhancement Parameters (Allow Substitution):

Clock Frequency: Higher frequencies (20 MHz) are backward compatible
Write Cycle Time: Faster cycle times (4ms vs 5ms) are acceptable
Moisture Sensitivity Level: Different MSL ratings do not affect electrical compatibility

Packaging Format Variations (Allow Substitution):

Tube packaging can be substituted with Tape & Reel (TR) or Cut Tape (CT) & Digi-Reel® formats for the same electrical specifications

All substitute parts listed maintain the core 4Kbit SPI EEPROM architecture with 8-TSSOP packaging and are manufactured by qualified semiconductor suppliers (Microchip Technology, STMicroelectronics, Renesas Electronics Corporation).

Parameter Comparison

Part Number	Manufacturer	Memory Size	Clock Frequency	Supply Voltage	Operating Temp	Write Cycle Time	Package	Packaging Format	MSL
25AA040AX-I/ST	Microchip Technology	4Kbit	10 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	Tube	1 (Unlimited)
AT25040B-XHL-B	Microchip Technology	4Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	Tube	3 (168 Hours)
AT25040B-XHL-T	Microchip Technology	4Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	Tape & Reel (TR)	3 (168 Hours)
M95040-DFDW6TP	STMicroelectronics	4Kbit	20 MHz	1.7V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	Tape & Reel (TR)	1 (Unlimited)
M95040-DRDW3TP/K	STMicroelectronics	4Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 125°C	4ms	8-TSSOP	Cut Tape (CT) & Digi-Reel®	1 (Unlimited)
M95040-DRDW8TP/K	STMicroelectronics	4Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 105°C	4ms	8-TSSOP	Tape & Reel (TR)	1 (Unlimited)
M95040-RDW6TP	STMicroelectronics	4Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	Cut Tape (CT) & Digi-Reel®	1 (Unlimited)
M95040-WDW6TP	STMicroelectronics	4Kbit	20 MHz	2.5V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	Tape & Reel (TR)	1 (Unlimited)
R1EX25004ATA00I#S0	Renesas Electronics Corporation	4Kbit	5 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	Tape & Reel (TR)	1 (Unlimited)

Engineering Selection Recommendations

Direct Substitutes (Identical or Enhanced Specifications):

AT25040B-XHL-B and AT25040B-XHL-T are direct substitutes from Microchip Technology with doubled clock frequency (20 MHz) while maintaining identical supply voltage range and operating temperature. Both parts are ROHS3 compliant and active product status. The primary difference is packaging format: AT25040B-XHL-B is supplied in Tube format matching the original, while AT25040B-XHL-T is supplied in Tape & Reel format for automated assembly processes.

M95040-RDW6TP from STMicroelectronics is a direct substitute with 20 MHz clock frequency, matching supply voltage and operating temperature specifications. This part is supplied in Cut Tape & Digi-Reel® format and maintains MSL 1 rating.

Substitutes with Extended Temperature Range:

M95040-DRDW3TP/K and M95040-DRDW8TP/K are STMicroelectronics parts qualified to AEC-Q100 automotive standards with extended operating temperature ranges (-40°C to 125°C and -40°C to 105°C respectively). Both feature 20 MHz clock frequency and 4ms write cycle time. These parts are suitable for applications requiring automotive-grade reliability.

Substitutes with Reduced Clock Frequency:

R1EX25004ATA00I#S0 from Renesas Electronics Corporation operates at 5 MHz clock frequency, which is lower than the original 10 MHz specification. This part maintains identical supply voltage range and operating temperature. Selection of this part is appropriate only when system clock requirements do not exceed 5 MHz.

Substitutes with Restricted Supply Voltage:

M95040-WDW6TP has a minimum supply voltage of 2.5V, which is higher than the original 1.8V minimum. This part is suitable only for systems with supply voltages of 2.5V or higher.

Frequently Asked Questions (FAQ)

Q: Can I substitute the 25AA040AX-I/ST with a part having 20 MHz clock frequency?

A: Yes. The 25AA040AX-I/ST operates at 10 MHz. Substitute parts with 20 MHz clock frequency (AT25040B-XHL-B, AT25040B-XHL-T, M95040-DFDW6TP, M95040-DRDW3TP/K, M95040-DRDW8TP/K, M95040-RDW6TP, M95040-WDW6TP) are fully compatible. Higher clock frequency provides enhanced performance without affecting backward compatibility with 10 MHz system designs.

Q: What is the difference between Tube, Tape & Reel, and Cut Tape packaging?

A: Tube packaging is used for manual component handling and small-volume assembly. Tape & Reel (TR) packaging is used for automated pick-and-place assembly equipment. Cut Tape (CT) & Digi-Reel® is a hybrid format combining cut tape strips with reel storage. All three formats contain identical electrical components; the choice depends on manufacturing process requirements.

Q: Can I use R1EX25004ATA00I#S0 as a substitute if my system requires 10 MHz operation?

A: No. The R1EX25004ATA00I#S0 operates at 5 MHz maximum clock frequency. This part is suitable only for applications with clock requirements of 5 MHz or lower. For 10 MHz or higher operation, select substitute parts with 10 MHz or 20 MHz specifications.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance status, matching the environmental compliance of the original 25AA040AX-I/ST.

Q: What is the difference between MSL 1 and MSL 3 ratings?

A: MSL (Moisture Sensitivity Level) 1 indicates unlimited shelf life without moisture control. MSL 3 requires storage in controlled humidity conditions with a maximum shelf life of 168 hours after opening the moisture barrier bag. Parts with MSL 1 (such as M95040 series and R1EX25004ATA00I#S0) offer greater flexibility in storage and handling compared to MSL 3 parts (AT25040B-XHL series).

Q: Can I use M95040-WDW6TP in a system with 1.8V supply voltage?

A: No. The M95040-WDW6TP has a minimum supply voltage specification of 2.5V. This part is not suitable for systems operating at 1.8V. Select substitute parts with 1.8V minimum supply voltage specification (25AA040AX-I/ST, AT25040B-XHL-B, AT25040B-XHL-T, M95040-DRDW3TP/K, M95040-DRDW8TP/K, M95040-RDW6TP, R1EX25004ATA00I#S0).

Q: Are automotive-qualified parts available as substitutes?

A: Yes. M95040-DRDW3TP/K and M95040-DRDW8TP/K are qualified to AEC-Q100 automotive standards. These parts feature extended operating temperature ranges and are suitable for automotive and industrial applications requiring enhanced reliability certification.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message