25AA640XT-I/ST EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The 25AA640XT-I/ST is a 64Kbit Serial Peripheral Interface (SPI) EEPROM memory IC manufactured by Microchip Technology. This non-volatile memory device operates at 1 MHz clock frequency with 8K x 8 memory organization in an 8-TSSOP surface mount package. The part is currently active in production with 860 units in stock.

Equivalent and substitute parts are identified when design requirements allow flexibility in clock frequency, operating temperature range, or manufacturer selection while maintaining core electrical and mechanical compatibility. Substitutes must preserve the 64Kbit capacity, SPI interface, 8-TSSOP package form factor, and supply voltage range compatibility.

Key Parameters

Parameter	Value
Memory Size	64Kbit
Memory Organization	8K x 8
Memory Interface	SPI
Clock Frequency	1 MHz
Voltage Supply Range	1.8V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Package / Case	8-TSSOP (0.173", 4.40mm Width)
Write Cycle Time	5ms
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following core parameters:

Memory Capacity & Organization: All substitutes must maintain 64Kbit capacity with 8K x 8 organization
Interface Protocol: SPI interface is mandatory for all substitutes
Package Compatibility: 8-TSSOP package with 0.173" width (4.40mm) is required for mechanical and electrical compatibility
Supply Voltage Range: Substitutes must support the 1.8V ~ 5.5V range or a subset thereof
Write Cycle Time: Substitutes with equal or faster write cycle times (≤5ms) are acceptable
Clock Frequency: Substitutes operating at equal or higher clock frequencies than 1 MHz are acceptable

Substitutes are grouped by manufacturer and performance tier. Higher clock frequency variants provide enhanced performance headroom while maintaining backward compatibility with 1 MHz operation through software configuration.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Clock Frequency	Voltage Supply	Operating Temp	Write Cycle Time	Package	Inventory
25AA640XT-I/ST	Microchip Technology	64Kbit	1 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	860
25AA640AT-I/ST	Microchip Technology	64Kbit	10 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	5875
AT25640B-XHL-T	Microchip Technology	64Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	19863
CAV25640YE-GT3	onsemi	64Kbit	10 MHz	2.5V ~ 5.5V	-40°C ~ 125°C	5ms	8-TSSOP	1180
M95640-DFDW6TP	STMicroelectronics	64Kbit	20 MHz	1.7V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	1140
M95640-DRDW3TP/K	STMicroelectronics	64Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 125°C	4ms	8-TSSOP	17589
M95640-DRDW8TP/K	STMicroelectronics	64Kbit	16 MHz	1.8V ~ 5.5V	-40°C ~ 105°C	4ms	8-TSSOP	16302
M95640-RDW6TP	STMicroelectronics	64Kbit	20 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	45400
R1EX25064ATA00I#S0	Renesas Electronics Corporation	64Kbit	5 MHz	1.8V ~ 5.5V	-40°C ~ 85°C	5ms	8-TSSOP	2328

Engineering Selection Recommendations

Microchip Technology 25AA640 Series: The 25AA640AT-I/ST and AT25640B-XHL-T variants offer higher clock frequencies (10 MHz and 20 MHz respectively) while maintaining identical supply voltage and temperature ranges. The AT25640B-XHL-T is verified for DiGi-Electronics programmability and carries the highest inventory availability (19,863 units).

STMicroelectronics M95640 Series: Multiple variants provide 16 MHz to 20 MHz clock frequencies with extended temperature ranges up to 125°C. The M95640-DRDW3TP/K and M95640-DRDW8TP/K are qualified to AEC-Q100 automotive standards with write cycle times of 4ms. The M95640-RDW6TP offers the largest inventory (45,400 units) with 20 MHz operation and standard temperature range.

onsemi CAV25640YE-GT3: Automotive-qualified variant with AEC-Q100 certification, 10 MHz operation, and extended temperature range to 125°C. Supply voltage range begins at 2.5V (narrower than the main part).

Renesas Electronics R1EX25064ATA00I#S0: Intermediate performance option at 5 MHz with standard temperature and voltage ranges matching the main part.

All substitutes maintain ROHS3 compliance and identical 8-TSSOP package specifications. Selection should be based on required clock frequency headroom, temperature operating range, automotive qualification requirements, and inventory availability.

Frequently Asked Questions (FAQ)

Q: Can I substitute the 25AA640XT-I/ST with a higher frequency variant like the AT25640B-XHL-T?

A: Yes. The AT25640B-XHL-T operates at 20 MHz and is fully compatible with the 25AA640XT-I/ST at the electrical and mechanical level. The 1 MHz specification of the original part represents the minimum operating frequency; higher frequency variants operate at reduced clock speeds through software configuration.

Q: What is the difference between the Microchip 25AA640AT-I/ST and AT25640B-XHL-T?

A: Both are Microchip 64Kbit SPI EEPROM devices in 8-TSSOP packages. The 25AA640AT-I/ST operates at 10 MHz, while the AT25640B-XHL-T operates at 20 MHz. The AT25640B-XHL-T is verified for DiGi-Electronics programmability. Both support identical voltage and temperature ranges.

Q: Are the STMicroelectronics M95640 variants with AEC-Q100 qualification backward compatible?

A: Yes. The M95640-DRDW3TP/K and M95640-DRDW8TP/K are AEC-Q100 qualified automotive-grade variants with identical SPI interface and 8-TSSOP package. They operate at higher clock frequencies (20 MHz and 16 MHz respectively) and support extended temperature ranges to 125°C.

Q: Does the onsemi CAV25640YE-GT3 work in applications requiring 1.8V supply?

A: No. The CAV25640YE-GT3 has a minimum supply voltage of 2.5V, whereas the 25AA640XT-I/ST supports 1.8V minimum. This variant is suitable only for applications with 2.5V or higher supply voltages.

Q: What is the inventory advantage of the M95640-RDW6TP?

A: The M95640-RDW6TP has the highest inventory availability at 45,400 units. It provides 20 MHz operation with standard -40°C to 85°C temperature range and 1.8V to 5.5V supply voltage compatibility, matching the core electrical specifications of the original part.

Q: Can I use the R1EX25064ATA00I#S0 as a direct replacement?

A: Yes. The R1EX25064ATA00I#S0 is a Renesas Electronics 64Kbit SPI EEPROM with identical supply voltage (1.8V ~ 5.5V), temperature range (-40°C ~ 85°C), and 8-TSSOP package. It operates at 5 MHz, providing intermediate performance between the 1 MHz original and higher frequency variants.

Q: Are all substitutes ROHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance and identical moisture sensitivity level (MSL 1 - Unlimited).

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