Equivalent & Substitute Parts for 93LC66XT/SN

Part Overview

The 93LC66XT/SN is a 4Kbit EEPROM memory IC manufactured by Microchip Technology, featuring Microwire serial interface protocol with 2 MHz clock frequency. This device is classified as obsolete, which necessitates identification of active equivalent and substitute parts for ongoing design support and procurement continuity. The part is packaged in 8-SOIC surface mount configuration and operates across a 2.5V to 5.5V supply voltage range with industrial temperature specifications (0°C to 70°C).

Key Parameters

Parameter	Value
Memory Size	4Kbit
Memory Format	EEPROM
Memory Interface	Microwire
Clock Frequency	2 MHz
Memory Organization	512 x 8, 256 x 16
Write Cycle Time	10ms
Voltage Supply Range	2.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C
Package Type	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the 93LC66XT/SN is determined by the following critical parameters: memory size (4Kbit), memory format (EEPROM), interface protocol (Microwire), package type (8-SOIC), and mounting configuration (surface mount). Parts are grouped into two categories based on operational specifications:

Category 1: Direct Electrical Equivalents (2 MHz Operation) Parts maintaining identical clock frequency (2 MHz), write cycle time (10ms), and voltage supply range (2.5V ~ 5.5V) with matching or extended temperature operating ranges. These parts are pin-compatible and functionally interchangeable without circuit modification.

Category 2: Enhanced Performance Alternatives (3 MHz Operation) Parts featuring upgraded clock frequency (3 MHz), reduced write cycle time (6ms), and extended voltage supply range (1.8V ~ 5.5V). These parts offer improved performance characteristics and broader operational flexibility while maintaining identical package and interface specifications.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Clock Frequency	Write Cycle Time	Voltage Supply	Operating Temperature	Product Status	Package
93LC66XT/SN	Microchip Technology	4Kbit	2 MHz	10ms	2.5V ~ 5.5V	0°C ~ 70°C	Obsolete	8-SOIC
93LC66X/SN	Microchip Technology	4Kbit	2 MHz	10ms	2.5V ~ 5.5V	0°C ~ 70°C	Active	8-SOIC
93AA66C-I/SN	Microchip Technology	4Kbit	3 MHz	6ms	1.8V ~ 5.5V	-40°C ~ 85°C	Active	8-SOIC
93AA66CT-I/SN	Microchip Technology	4Kbit	3 MHz	6ms	1.8V ~ 5.5V	-40°C ~ 85°C	Active	8-SOIC
93AA66CXT-I/SN	Microchip Technology	4Kbit	3 MHz	6ms	1.8V ~ 5.5V	-40°C ~ 85°C	Active	8-SOIC
93AA66T-I/SN	Microchip Technology	4Kbit	2 MHz	10ms	1.8V ~ 5.5V	-40°C ~ 85°C	Active	8-SOIC
93AA66T/SN	Microchip Technology	4Kbit	2 MHz	10ms	1.8V ~ 5.5V	0°C ~ 70°C	Active	8-SOIC
93AA66XT/SN	Microchip Technology	4Kbit	2 MHz	10ms	1.8V ~ 5.5V	0°C ~ 70°C	Active	8-SOIC
93LC66CT-E/SN	Microchip Technology	4Kbit	3 MHz	6ms	2.5V ~ 5.5V	-40°C ~ 125°C	Active	8-SOIC
93LC66CT-I/SN	Microchip Technology	4Kbit	3 MHz	6ms	2.5V ~ 5.5V	-40°C ~ 85°C	Active	8-SOIC
93LC66CXT-E/SN	Microchip Technology	4Kbit	3 MHz	6ms	2.5V ~ 5.5V	-40°C ~ 125°C	Active	8-SOIC

Engineering Selection Recommendations

Primary Recommendation: 93LC66X/SN This part provides direct electrical and functional equivalence to the 93LC66XT/SN with active product status. It maintains identical electrical specifications (2 MHz clock frequency, 10ms write cycle time, 2.5V to 5.5V supply range) and operating temperature range (0°C to 70°C). The transition from obsolete to active status ensures long-term availability and supply chain continuity.

Secondary Recommendation: 93AA66T/SN or 93AA66XT/SN These parts offer extended voltage supply range (1.8V to 5.5V) and expanded operating temperature range (-40°C to 85°C) while maintaining 2 MHz clock frequency and 10ms write cycle time. Selection is appropriate when designs require lower supply voltage operation or broader temperature specifications.

Performance Enhancement Option: 93LC66CT-I/SN or 93LC66CXT-E/SN These parts provide 3 MHz clock frequency and 6ms write cycle time, delivering improved performance over the original specification. The 93LC66CT-E/SN extends operating temperature to -40°C to 125°C, suitable for high-temperature applications. These parts maintain the 2.5V to 5.5V supply range of the original device.

All recommended substitutes are ROHS3 compliant, carry MSL rating of 1 (Unlimited), and maintain Microwire interface compatibility with the original 93LC66XT/SN design.

Frequently Asked Questions (FAQ)

Q: Can 93LC66X/SN be used as a direct replacement for 93LC66XT/SN? A: Yes. Both parts share identical electrical specifications, memory organization, clock frequency, write cycle time, voltage supply range, and operating temperature range. The primary difference is product status: 93LC66X/SN is active while 93LC66XT/SN is obsolete. Pin configuration and package dimensions are identical.

Q: What is the difference between 2 MHz and 3 MHz clock frequency variants? A: The 2 MHz variants (93LC66XT/SN, 93LC66X/SN, 93AA66T/SN, 93AA66XT/SN) require 10ms write cycle time per word or page. The 3 MHz variants (93AA66C-I/SN, 93LC66CT-I/SN, 93LC66CXT-E/SN) reduce write cycle time to 6ms, enabling faster programming operations. Both maintain identical memory capacity and Microwire interface protocol.

Q: Are 93AA66 series parts compatible with 93LC66 series designs? A: Compatibility depends on voltage supply requirements. The 93AA66 series operates from 1.8V to 5.5V, while 93LC66 series operates from 2.5V to 5.5V. If the design uses supply voltages below 2.5V, only 93AA66 variants are suitable. For designs operating at 2.5V and above, both series are electrically compatible with identical pin configuration and Microwire protocol.

Q: What packaging options are available for these substitutes? A: All listed substitutes are available in 8-SOIC surface mount package (0.154" width, 3.90mm). Packaging variants include Tube, Cut Tape (CT) & Digi-Reel, and Tape & Reel (TR) configurations. The specific packaging designation does not affect electrical or functional compatibility; it reflects distribution and handling format only.

Q: Can I use 93LC66CT-E/SN in place of 93LC66XT/SN for industrial temperature applications? A: Yes, with performance enhancement. The 93LC66CT-E/SN maintains the 2.5V to 5.5V supply range of the original part and extends operating temperature to -40°C to 125°C. It also provides improved clock frequency (3 MHz) and reduced write cycle time (6ms). This part is suitable for applications requiring extended temperature operation beyond the original 0°C to 70°C range.

Q: What is the significance of the temperature grade suffix (I, E, XT)? A: Temperature grade suffixes indicate operating temperature range specifications. The "I" suffix typically denotes industrial temperature range (-40°C to 85°C), while "E" denotes extended temperature range (-40°C to 125°C). The "XT" designation indicates extended specifications. These suffixes do not affect pin compatibility or Microwire protocol implementation.

Q: Are all listed substitutes RoHS3 compliant? A: Yes. All substitute parts listed carry ROHS3 compliance certification and MSL rating of 1 (Unlimited moisture sensitivity level). This ensures compatibility with RoHS3 regulated assembly processes and environmental requirements.

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