25LC128XT-I/ST EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The 25LC128XT-I/ST is a 128Kbit 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 85°C. The device is ROHS3 compliant and currently in active product status. Equivalent and substitute parts are necessary when the primary part number becomes unavailable, when alternative packaging formats are required, or when enhanced performance specifications (higher clock frequency, extended temperature range, or automotive qualification) are needed for specific applications.

Key Parameters

Parameter	Value
Memory Size	128Kbit
Memory Organization	16K x 8
Memory Interface	SPI
Clock Frequency	10 MHz
Write Cycle Time	5ms
Voltage Supply Range	2.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Package / Case	8-TSSOP (0.173", 4.40mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the 25LC128XT-I/ST is determined by strict adherence to the following core parameters: 128Kbit memory capacity, 16K x 8 memory organization, SPI interface protocol, 8-TSSOP package format with 0.173" width and 4.40mm dimensions, surface mount mounting type, and ROHS3 compliance. All substitute parts must maintain these specifications without exception.

Secondary parameters that may vary between the primary part and substitutes include clock frequency (10 MHz or higher), write cycle time (5ms or faster), supply voltage range (2.5V–5.5V or wider ranges such as 1.8V–5.5V), operating temperature range (-40°C to 85°C or extended ranges), packaging format (Tape & Reel, Cut Tape, or Tube), and product status (Active or Obsolete). Automotive-grade variants with AEC-Q100 qualification and extended temperature ratings represent enhanced alternatives suitable for demanding applications.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Clock Frequency	Write Cycle Time	Voltage Supply	Operating Temperature	Packaging	Product Status
25LC128XT-I/ST	Microchip Technology	128Kbit	10 MHz	5ms	2.5V ~ 5.5V	-40°C ~ 85°C	Tape & Reel	Active
25AA128T-I/ST	Microchip Technology	128Kbit	10 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	Cut Tape & Digi-Reel	Active
25LC128T-I/ST	Microchip Technology	128Kbit	10 MHz	5ms	2.5V ~ 5.5V	-40°C ~ 85°C	Cut Tape & Digi-Reel	Active
AT25128B-XHL-B	Microchip Technology	128Kbit	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	Tube	Active
AT25128B-XHL-T	Microchip Technology	128Kbit	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	Cut Tape & Digi-Reel	Active
CAT25128YI-G	onsemi	128Kbit	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	Not Specified	Obsolete
CAT25128YI-GT3	onsemi	128Kbit	20 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	Tape & Reel	Active
CAV25128YE-GT3	onsemi	128Kbit	10 MHz	5ms	2.5V ~ 5.5V	-40°C ~ 125°C	Tape & Reel	Active
M95128-DRDW3TP/K	STMicroelectronics	128Kbit	20 MHz	4ms	1.8V ~ 5.5V	-40°C ~ 125°C	Cut Tape & Digi-Reel	Active
M95128-DRDW8TP/K	STMicroelectronics	128Kbit	20 MHz	4ms	1.8V ~ 5.5V	-40°C ~ 105°C	Cut Tape & Digi-Reel	Active
M95128-DWDW4TP/K	STMicroelectronics	128Kbit	20 MHz	4ms	2.5V ~ 5.5V	-40°C ~ 145°C	Cut Tape & Digi-Reel	Active

Engineering Selection Recommendations

Direct substitution candidates maintaining identical electrical and mechanical specifications are 25LC128T-I/ST (Microchip Technology, Cut Tape & Digi-Reel packaging) and 25AA128T-I/ST (Microchip Technology, extended 1.8V minimum supply voltage, Cut Tape & Digi-Reel packaging). Both are active products with ROHS3 compliance and identical memory organization, interface protocol, and thermal characteristics.

For applications requiring enhanced clock frequency performance, AT25128B-XHL-B and AT25128B-XHL-T (Microchip Technology, 20 MHz) and CAT25128YI-GT3 (onsemi, 20 MHz, active status) provide doubled clock frequency while maintaining 5ms write cycle time and ROHS3 compliance. These parts support extended lower voltage operation (1.8V minimum).

For automotive and extended temperature applications, CAV25128YE-GT3 (onsemi, AEC-Q100 qualified, -40°C to 125°C) and M95128-DRDW3TP/K (STMicroelectronics, AEC-Q100 qualified, -40°C to 125°C, 4ms write cycle) provide automotive-grade reliability. M95128-DWDW4TP/K (STMicroelectronics, -40°C to 145°C, 2.5V supply range) extends temperature capability to 145°C for extreme environment applications.

CAT25128YI-G (onsemi) is marked obsolete and should not be selected for new designs despite technical compatibility.

Frequently Asked Questions (FAQ)

Q: Can 25AA128T-I/ST replace 25LC128XT-I/ST in all applications?

A: Yes, with one consideration. The 25AA128T-I/ST supports a lower minimum supply voltage (1.8V versus 2.5V), making it compatible with all 25LC128XT-I/ST applications. The primary difference is packaging format (Cut Tape & Digi-Reel versus Tape & Reel). Verify your assembly process accommodates the packaging change.

Q: What is the advantage of AT25128B-XHL-T over 25LC128XT-I/ST?

A: AT25128B-XHL-T operates at 20 MHz clock frequency (double the 10 MHz of 25LC128XT-I/ST) while maintaining identical 5ms write cycle time. This provides faster read operations for data-intensive applications. It also supports 1.8V minimum supply voltage. Both are ROHS3 compliant and active products.

Q: Are STMicroelectronics M95128 variants suitable for consumer applications?

A: Yes. M95128-DRDW3TP/K, M95128-DRDW8TP/K, and M95128-DWDW4TP/K all meet ROHS3 compliance and are active products. They feature faster 4ms write cycle time compared to the 5ms of 25LC128XT-I/ST. All three carry AEC-Q100 automotive qualification, which does not restrict use in consumer applications but indicates enhanced reliability testing.

Q: Why would I select CAV25128YE-GT3 instead of other substitutes?

A: CAV25128YE-GT3 is the only onsemi option matching the exact 10 MHz clock frequency and 2.5V–5.5V supply range of 25LC128XT-I/ST. It extends operating temperature to -40°C to 125°C and carries AEC-Q100 automotive qualification. Select this part when clock frequency must remain at 10 MHz and extended temperature operation is required.

Q: Is CAT25128YI-G still available for purchase?

A: CAT25128YI-G is marked obsolete. Although 939 pieces remain in inventory, this part should not be selected for new designs. Use CAT25128YI-GT3 (active status, Tape & Reel packaging) as the current onsemi equivalent.

Q: What is the difference between M95128-DRDW3TP/K and M95128-DWDW4TP/K?

A: Both operate at 20 MHz with 4ms write cycle time and AEC-Q100 qualification. M95128-DRDW3TP/K supports -40°C to 125°C and 1.8V–5.5V supply. M95128-DWDW4TP/K supports -40°C to 145°C and 2.5V–5.5V supply. Select M95128-DWDW4TP/K for extreme high-temperature environments; select M95128-DRDW3TP/K for standard automotive temperature ranges with lower voltage operation.

Q: Can I use a 20 MHz part as a drop-in replacement for a 10 MHz part?

A: Yes. Higher clock frequency is backward compatible. A 20 MHz EEPROM operates correctly in circuits designed for 10 MHz operation. The system will not utilize the additional speed capability, but electrical and functional compatibility is maintained.

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