93LC66B/ST EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The 93LC66B/ST is a 4Kbit non-volatile EEPROM memory IC manufactured by Microchip Technology, featuring Microwire serial interface protocol and operating at 2 MHz clock frequency. This component is designed for applications requiring persistent data storage with low power consumption and wide voltage tolerance. The part is currently in active production status with RoHS3 compliance and unlimited moisture sensitivity rating. Substitute parts are identified when equivalent electrical specifications, memory organization, interface protocol, and physical packaging allow direct functional replacement in circuit designs.

Key Parameters

Parameter	Specification
Memory Type	Non-Volatile EEPROM
Memory Size	4Kbit
Memory Organization	256 x 16
Memory Interface	Microwire
Clock Frequency	2 MHz
Write Cycle Time	6ms
Voltage Supply Range	2.5V ~ 5.5V
Operating Temperature	0°C ~ 70°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 93LC66B/ST are qualified based on the following critical parameters that must remain constant or compatible:

Memory capacity: 4Kbit with 256 x 16 organization
Serial interface protocol: Microwire
Clock frequency: 2 MHz operation
Package form factor: 8-TSSOP with 0.173" width and 4.40mm dimensions
Surface mount technology compatibility
Non-volatile EEPROM technology
RoHS3 compliance and MSL Level 1 rating

Substitutes are grouped into two categories: direct pin-compatible replacements from Microchip Technology (93AA66B-I/ST, 93LC66B-I/ST) and cross-manufacturer alternatives (BR93L66FVT-WE2 from Rohm Semiconductor) that maintain electrical and mechanical equivalence.

Parameter Comparison

Parameter	93LC66B/ST	93AA66B-I/ST	93LC66B-I/ST	BR93L66FVT-WE2
Manufacturer	Microchip Technology	Microchip Technology	Microchip Technology	Rohm Semiconductor
Memory Size	4Kbit	4Kbit	4Kbit	4Kbit
Memory Organization	256 x 16	256 x 16	256 x 16	256 x 16
Memory Interface	Microwire	Microwire	Microwire	Microwire
Clock Frequency	2 MHz	2 MHz	2 MHz	2 MHz
Write Cycle Time	6ms	6ms	6ms	5ms
Voltage Supply Range	2.5V ~ 5.5V	1.8V ~ 5.5V	2.5V ~ 5.5V	1.8V ~ 5.5V
Operating Temperature	0°C ~ 70°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Package / Case	8-TSSOP (0.173", 4.40mm)	8-TSSOP (0.173", 4.40mm)	8-TSSOP (0.173", 4.40mm)	8-TSSOP (0.173", 4.40mm)
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Active	Active	Active	Active

Engineering Selection Recommendations

93AA66B-I/ST (Microchip Technology): This substitute offers extended voltage tolerance (1.8V minimum) and expanded operating temperature range (-40°C to 85°C) compared to the primary part. However, programmability verification status differs. Selection is appropriate for applications requiring lower supply voltage operation or wider temperature extremes within the same manufacturer ecosystem.

93LC66B-I/ST (Microchip Technology): This substitute maintains identical voltage supply range (2.5V ~ 5.5V) to the primary part while extending operating temperature range to -40°C to 85°C. Programmability verification status matches the primary part. This represents the most direct functional equivalent with enhanced temperature performance.

BR93L66FVT-WE2 (Rohm Semiconductor): This cross-manufacturer substitute provides extended voltage tolerance (1.8V minimum), expanded operating temperature range (-40°C to 85°C), and marginally faster write cycle time (5ms versus 6ms). All parts maintain RoHS3 compliance, MSL Level 1 rating, and identical memory specifications. Selection of this part introduces cross-manufacturer sourcing with verified programmability status.

Frequently Asked Questions (FAQ)

Q: Can 93AA66B-I/ST replace 93LC66B/ST in all applications? A: Functional replacement is possible for applications operating within 2.5V to 5.5V supply range and 0°C to 70°C temperature limits. The 93AA66B-I/ST supports lower voltage operation (1.8V) and wider temperature range, making it suitable for designs requiring these extended specifications. Verify circuit design constraints before substitution.

Q: What is the difference between 93LC66B/ST and 93LC66B-I/ST? A: Both parts are manufactured by Microchip Technology with identical electrical specifications and packaging. The primary difference is operating temperature range: 93LC66B/ST operates 0°C to 70°C, while 93LC66B-I/ST operates -40°C to 85°C. Memory capacity, interface protocol, and physical package remain identical.

Q: Is BR93L66FVT-WE2 pin-compatible with 93LC66B/ST? A: Yes. Both parts use 8-TSSOP packaging with identical pinout for Microwire serial interface operation. The Rohm part is electrically and mechanically compatible for direct PCB replacement. Verify firmware or software compatibility with cross-manufacturer components if applicable to your design.

Q: Does voltage supply range affect substitution eligibility? A: Yes. The primary part operates 2.5V to 5.5V. Substitutes with 1.8V minimum (93AA66B-I/ST, BR93L66FVT-WE2) are backward compatible with 2.5V designs but enable additional low-voltage applications. Designs operating below 2.5V require substitutes with extended lower voltage specification.

Q: Are all substitute parts RoHS3 compliant? A: Yes. All listed substitutes (93AA66B-I/ST, 93LC66B-I/ST, BR93L66FVT-WE2) maintain RoHS3 compliance and MSL Level 1 (unlimited) moisture sensitivity rating, matching the primary part specifications.

Q: What is the significance of write cycle time differences? A: The primary part and most substitutes specify 6ms write cycle time. BR93L66FVT-WE2 specifies 5ms, representing marginally faster write performance. This difference is negligible for most applications but may provide minor timing advantages in high-speed data logging or rapid sequential write operations.

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