25LC640AX-E/ST EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The 25LC640AX-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 5ms write cycle time and supports supply voltages from 2.5V to 5.5V across an operating temperature range of -40°C to 125°C. The device is ROHS3 compliant and carries Active product status. Equivalent and substitute parts are identified based on matching memory capacity, interface protocol, package type, and electrical operating parameters to ensure direct functional replacement in circuit applications.

Key Parameters

Parameter	Value
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 Type	8-TSSOP (0.173", 4.40mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the 25LC640AX-E/ST are grouped based on the following critical parameters that determine functional compatibility:

Primary Matching Criteria:

Memory capacity: 64Kbit
Memory organization: 8K x 8
Interface protocol: SPI
Package type: 8-TSSOP surface mount
Pin count and pinout compatibility: 8-pin configuration

Secondary Compatibility Parameters:

Clock frequency: 10 MHz or higher (backward compatible)
Supply voltage range: Must encompass or exceed 2.5V ~ 5.5V
Operating temperature range: Must support -40°C minimum and 125°C maximum, or equivalent industrial/automotive grades
Write cycle time: 5ms or faster
RoHS compliance status

Substitutes are valid when all primary criteria are met and secondary parameters do not impose operational restrictions in the target application.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Clock Frequency (MHz)	Supply Voltage (V)	Operating Temp (°C)	Write Cycle (ms)	Package	RoHS Status
25LC640AX-E/ST	Microchip Technology	64Kbit	10	2.5 ~ 5.5	-40 ~ 125	5	8-TSSOP	ROHS3
25LC640A-E/ST	Microchip Technology	64Kbit	10	2.5 ~ 5.5	-40 ~ 125	5	8-TSSOP	ROHS3
AT25640B-XHL-B	Microchip Technology	64Kbit	20	1.8 ~ 5.5	-40 ~ 85	5	8-TSSOP	ROHS3
AT25640B-XHL-T	Microchip Technology	64Kbit	20	1.8 ~ 5.5	-40 ~ 85	5	8-TSSOP	ROHS3
CAV25640YE-GT3	onsemi	64Kbit	10	2.5 ~ 5.5	-40 ~ 125	5	8-TSSOP	ROHS3
M95640-DFDW6TP	STMicroelectronics	64Kbit	20	1.7 ~ 5.5	-40 ~ 85	5	8-TSSOP	ROHS3
M95640-DRDW3TP/K	STMicroelectronics	64Kbit	20	1.8 ~ 5.5	-40 ~ 125	4	8-TSSOP	ROHS3
M95640-DRDW8TP/K	STMicroelectronics	64Kbit	16	1.8 ~ 5.5	-40 ~ 105	4	8-TSSOP	ROHS3
M95640-DWDW4TP/K	STMicroelectronics	64Kbit	20	2.5 ~ 5.5	-40 ~ 145	4	8-TSSOP	ROHS3
R1EX25064ATA00I#S0	Renesas Electronics Corporation	64Kbit	5	1.8 ~ 5.5	-40 ~ 85	5	8-TSSOP	ROHS3

Engineering Selection Recommendations

Direct Equivalent (Identical Specifications): The 25LC640A-E/ST from Microchip Technology is a direct equivalent with identical electrical and thermal specifications, matching the 10 MHz clock frequency, 2.5V to 5.5V supply range, and -40°C to 125°C operating temperature of the 25LC640AX-E/ST.

Higher Performance Substitutes (Enhanced Clock Frequency): The AT25640B-XHL-T, M95640-DRDW3TP/K, M95640-DRDW8TP/K, and M95640-DWDW4TP/K offer clock frequencies of 16 MHz to 20 MHz, providing faster SPI operation. These parts are suitable for applications where increased data throughput is beneficial. The M95640-DRDW3TP/K and M95640-DWDW4TP/K maintain the full -40°C to 125°C temperature range of the original part.

Automotive Grade Substitutes: The CAV25640YE-GT3, M95640-DRDW3TP/K, M95640-DRDW8TP/K, and M95640-DWDW4TP/K carry AEC-Q100 automotive qualification and are suitable for automotive applications requiring enhanced reliability standards.

Lower Clock Frequency Alternative: The R1EX25064ATA00I#S0 from Renesas operates at 5 MHz, half the frequency of the original part. This substitute is applicable only in applications where lower clock speeds are acceptable and where the reduced operating temperature range (-40°C to 85°C) does not conflict with system requirements.

Packaging Considerations: All substitute parts maintain the 8-TSSOP surface mount package with identical pinout compatibility. Tube and Tape & Reel packaging options are available across the substitute lineup to match procurement and assembly requirements.

Frequently Asked Questions (FAQ)

Q: Can the 25LC640A-E/ST directly replace the 25LC640AX-E/ST? A: Yes. The 25LC640A-E/ST is a direct equivalent with identical memory capacity, SPI interface, clock frequency, supply voltage range, operating temperature range, and 8-TSSOP package configuration.

Q: Are higher clock frequency parts backward compatible? A: Yes. Parts with 16 MHz or 20 MHz clock frequencies are backward compatible with the 10 MHz 25LC640AX-E/ST. The SPI interface remains identical, and faster clock operation does not prevent use in applications designed for 10 MHz operation.

Q: What is the difference between the AT25640B-XHL-B and AT25640B-XHL-T variants? A: Both parts are electrically identical with 20 MHz clock frequency and identical electrical specifications. The primary difference is packaging: AT25640B-XHL-B is supplied in Tube packaging, while AT25640B-XHL-T is supplied in Cut Tape & Digi-Reel format. The AT25640B-XHL-T also carries DiGi-Electronics Programmable verification.

Q: Can I use the R1EX25064ATA00I#S0 as a substitute? A: The R1EX25064ATA00I#S0 is functionally compatible but operates at 5 MHz clock frequency, which is half the speed of the original 25LC640AX-E/ST. Use this part only if your application does not require 10 MHz operation and if the -40°C to 85°C operating temperature range is sufficient.

Q: Which substitutes support the full -40°C to 125°C temperature range? A: The 25LC640A-E/ST, CAV25640YE-GT3, M95640-DRDW3TP/K, and M95640-DWDW4TP/K all support the full -40°C to 125°C operating temperature range matching the original part.

Q: Are all substitute parts ROHS3 compliant? A: Yes. All listed substitute parts carry ROHS3 compliance status, matching the environmental compliance of the 25LC640AX-E/ST.

Q: What is the significance of AEC-Q100 qualification? A: AEC-Q100 qualification indicates automotive-grade reliability testing and is required for automotive applications. The CAV25640YE-GT3, M95640-DRDW3TP/K, M95640-DRDW8TP/K, and M95640-DWDW4TP/K carry this qualification for use in automotive systems.

Q: Do all substitutes maintain the same write cycle time? A: Most substitutes maintain the 5ms write cycle time. However, the STMicroelectronics M95640 series parts (M95640-DRDW3TP/K, M95640-DRDW8TP/K, and M95640-DWDW4TP/K) feature a faster 4ms write cycle time, which is an improvement over the original specification.

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