25LC640AXT-E/ST EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The 25LC640AXT-E/ST is a 64Kbit 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 2.5V to 5.5V and temperature range of -40°C to 125°C. The part is ROHS3 compliant and currently in active production status with 963 units in stock. Equivalent and substitute parts are identified based on matching memory capacity, interface protocol, package type, and electrical operating parameters to ensure functional interchangeability in circuit applications.

Key Parameters

Parameter	25LC640AXT-E/ST
Memory Size	64Kbit
Memory Organization	8K 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 / Case	8-TSSOP (0.173", 4.40mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
MSL Rating	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the 25LC640AXT-E/ST are grouped based on the following critical parameters that determine functional interchangeability:

Primary Matching Criteria:

Memory Size: 64Kbit capacity
Memory Organization: 8K x 8 configuration
Memory Interface: SPI protocol
Package Type: 8-TSSOP form factor
Mounting Type: Surface Mount

Secondary Compatibility Parameters:

Clock Frequency: 10 MHz or higher (backward compatible)
Write Cycle Time: 5ms or faster (backward compatible)
Voltage Supply Range: Must encompass or exceed 2.5V ~ 5.5V minimum requirement
Operating Temperature: Must support -40°C minimum and 125°C maximum or higher
RoHS Compliance: ROHS3 Compliant status maintained

Substitutes are divided into two categories: direct equivalents matching all electrical specifications, and compatible alternatives with enhanced performance parameters (higher clock frequency, wider voltage range, extended temperature range) that maintain full backward compatibility.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Clock Frequency	Voltage Supply	Operating Temp	Write Cycle Time	Package	Packaging Type	Inventory	Status
25LC640AXT-E/ST	Microchip Technology	64Kbit	10 MHz	2.5V ~ 5.5V	-40°C ~ 125°C	5ms	8-TSSOP	Tape & Reel	963	Active
25LC640AT-E/ST	Microchip Technology	64Kbit	10 MHz	2.5V ~ 5.5V	-40°C ~ 125°C	5ms	8-TSSOP	Cut Tape & Digi-Reel	10400	Active
AT25640B-XHL-B	Microchip Technology	64Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	Tube	2300	Active
AT25640B-XHL-T	Microchip Technology	64Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	Cut Tape & Digi-Reel	19863	Active
CAV25640YE-GT3	onsemi	64Kbit	10 MHz	2.5V ~ 5.5V	-40°C ~ 125°C	5ms	8-TSSOP	Tape & Reel	1180	Active
M95640-DFDW6TP	STMicroelectronics	64Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	Cut Tape & Digi-Reel	1140	Active
M95640-DRDW3TP/K	STMicroelectronics	64Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 125°C	4ms	8-TSSOP	Cut Tape & Digi-Reel	17589	Active
M95640-DRDW8TP/K	STMicroelectronics	64Kbit	16 MHz	1.8V ~ 5.5V	-40°C ~ 105°C	4ms	8-TSSOP	Tape & Reel	16302	Active
M95640-DWDW4TP/K	STMicroelectronics	64Kbit	20 MHz	2.5V ~ 5.5V	-40°C ~ 145°C	4ms	8-TSSOP	Cut Tape & Digi-Reel	5460	Active
M95640-RDW6TP	STMicroelectronics	64Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	Cut Tape & Digi-Reel	45400	Active
R1EX25064ATA00I#S0	Renesas Electronics Corporation	64Kbit	5 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	Tape & Reel	2328	Active

Engineering Selection Recommendations

Direct Equivalent (Identical Specifications): The 25LC640AT-E/ST from Microchip Technology is a direct equivalent with identical electrical and thermal specifications. The only difference is packaging format (Cut Tape & Digi-Reel versus Tape & Reel). This part is suitable for direct substitution with higher inventory availability (10400 units).

Automotive Grade Alternatives: The M95640-DRDW3TP/K and M95640-DWDW4TP/K from STMicroelectronics are AEC-Q100 qualified automotive-grade parts. The M95640-DRDW3TP/K maintains the full -40°C to 125°C temperature range of the original part while offering 20 MHz clock frequency and 4ms write cycle time. The M95640-DWDW4TP/K extends the operating temperature to -40°C to 145°C and maintains 2.5V to 5.5V supply voltage compatibility.

Automotive Grade Equivalent (Matching Specifications): The CAV25640YE-GT3 from onsemi is an AEC-Q100 qualified automotive-grade part with identical electrical specifications (10 MHz, 2.5V ~ 5.5V, -40°C ~ 125°C) and matching write cycle time of 5ms.

Enhanced Performance Alternatives: Parts with 20 MHz clock frequency (AT25640B-XHL-T, M95640-DFDW6TP, M95640-DRDW3TP/K, M95640-DWDW4TP/K, M95640-RDW6TP) provide faster operation while maintaining backward compatibility. These are suitable when higher clock frequency is beneficial or when supply voltage range can be adjusted to 1.8V minimum.

Lower Clock Frequency Alternative: The R1EX25064ATA00I#S0 from Renesas Electronics operates at 5 MHz, which is half the original specification. This part is suitable only for applications where lower clock frequency is acceptable and does not require the full -40°C to 125°C temperature range (limited to -40°C to 85°C).

All substitute parts maintain ROHS3 compliance and MSL rating of 1 (Unlimited) except AT25640B-XHL-B which has MSL rating of 3 (168 Hours).

Frequently Asked Questions (FAQ)

Q: Can I use the 25LC640AT-E/ST as a direct replacement for the 25LC640AXT-E/ST?

A: Yes. The 25LC640AT-E/ST is a direct electrical equivalent with identical memory capacity (64Kbit), interface (SPI), clock frequency (10 MHz), voltage range (2.5V ~ 5.5V), temperature range (-40°C ~ 125°C), and package (8-TSSOP). The only difference is the packaging format (Cut Tape & Digi-Reel versus Tape & Reel), which does not affect circuit functionality.

Q: What is the difference between the Microchip 25LC640 series and the STMicroelectronics M95640 series?

A: Both series provide 64Kbit SPI EEPROM in 8-TSSOP packaging with identical memory organization (8K x 8). Key differences include clock frequency (M95640 offers up to 20 MHz versus 25LC640 at 10 MHz), write cycle time (M95640 typically 4ms versus 25LC640 at 5ms), and voltage supply range (M95640 starts at 1.8V versus 25LC640 at 2.5V). The M95640 series includes automotive-grade AEC-Q100 qualified variants.

Q: Can I substitute a 20 MHz part for the 10 MHz original specification?

A: Yes. Parts with higher clock frequency (20 MHz) are backward compatible with 10 MHz applications. The higher frequency capability does not affect operation at lower clock speeds. However, verify that your circuit design does not impose restrictions on maximum clock frequency.

Q: What does AEC-Q100 qualification mean for EEPROM selection?

A: AEC-Q100 is an automotive electronics qualification standard. Parts bearing this qualification (CAV25640YE-GT3, M95640-DRDW3TP/K, M95640-DRDW8TP/K, M95640-DWDW4TP/K) have undergone additional reliability testing and are suitable for automotive applications. Non-qualified parts are suitable for industrial and consumer applications.

Q: Why does the R1EX25064ATA00I#S0 operate at only 5 MHz?

A: The R1EX25064ATA00I#S0 from Renesas Electronics is designed for lower-speed applications. This part is suitable only when your circuit design does not require 10 MHz or higher clock frequency and when the operating temperature range of -40°C to 85°C is acceptable.

Q: What is the significance of MSL rating differences?

A: MSL (Moisture Sensitivity Level) rating indicates the maximum time a component can be exposed to moisture before soldering. MSL 1 (Unlimited) parts like the 25LC640AXT-E/ST and most substitutes have no time restriction. The AT25640B-XHL-B with MSL 3 (168 Hours) requires soldering within 168 hours of package opening if the component has been exposed to moisture above specified levels.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance status, matching the environmental compliance of the original 25LC640AXT-E/ST.

Q: Can I use the AT25640B-XHL-B (Tube packaging) in production assembly?

A: The AT25640B-XHL-B is supplied in Tube packaging rather than Tape & Reel or Cut Tape formats. Tube packaging is typically used for manual assembly or lower-volume applications. For automated pick-and-place assembly, use parts supplied in Tape & Reel (TR) or Cut Tape (CT) & Digi-Reel packaging formats.

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