Equivalent & Substitute Parts for 93LC66X/SN

Part Overview

The 93LC66X/SN is a 4Kbit EEPROM memory IC manufactured by Microchip Technology, featuring Microwire serial interface protocol and 2 MHz clock frequency. This non-volatile memory device is packaged in 8-SOIC surface mount configuration and operates across a 2.5V to 5.5V supply voltage range with 0°C to 70°C temperature specification. The part is ROHS3 compliant and maintains active product status. Equivalent and substitute parts are identified to address inventory availability, extended temperature range requirements, enhanced performance specifications, or alternative manufacturer sourcing.

Key Parameters

Parameter	Specification
Memory Type	Non-Volatile EEPROM
Memory Size	4Kbit
Memory Organization	512 x 8, 256 x 16
Memory Interface	Microwire
Clock Frequency	2 MHz
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 93LC66X/SN is determined by the following critical parameters: memory size (4Kbit), memory organization (512 x 8 or 256 x 16), memory interface protocol (Microwire), package type (8-SOIC), and mounting type (Surface Mount). Parts meeting these core requirements are classified as direct substitutes. Secondary parameters including clock frequency, write cycle time, voltage supply range, and operating temperature range define substitution categories:

Category A - Direct Substitutes (Identical Core Specifications): Parts with 2 MHz clock frequency, 10ms write cycle time, 2.5V ~ 5.5V supply voltage, and 0°C ~ 70°C operating temperature.

Category B - Enhanced Performance Substitutes: Parts with improved specifications such as higher clock frequency (3 MHz), faster write cycle time (5-6ms), extended temperature range (-40°C ~ 85°C), or wider supply voltage range (1.8V ~ 5.5V).

Category C - Alternative Interface Substitutes: Parts with different serial interface protocols (3-Wire Serial) but identical memory capacity and package configuration.

Category D - Cross-Manufacturer Substitutes: Parts from alternative manufacturers (onsemi, STMicroelectronics) meeting core memory and package specifications.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Interface	Clock Freq	Write Cycle	Voltage Range	Temp Range	Package	Inventory
93LC66X/SN	Microchip	4Kbit	Microwire	2 MHz	10ms	2.5V ~ 5.5V	0°C ~ 70°C	8-SOIC	980
93AA66/SN	Microchip	4Kbit	Microwire	2 MHz	10ms	1.8V ~ 5.5V	0°C ~ 70°C	8-SOIC	1169
93AA66C-I/SN	Microchip	4Kbit	Microwire	3 MHz	6ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-SOIC	2200
93LC66-I/SN	Microchip	4Kbit	Microwire	2 MHz	10ms	2.5V ~ 5.5V	-40°C ~ 85°C	8-SOIC	1578
93LC66/SN	Microchip	4Kbit	Microwire	2 MHz	10ms	2.5V ~ 5.5V	0°C ~ 70°C	8-SOIC	2220
93LC66C-I/SN	Microchip	4Kbit	Microwire	3 MHz	6ms	2.5V ~ 5.5V	-40°C ~ 85°C	8-SOIC	16166
AT93C66B-SSHM-B	Microchip	4Kbit	3-Wire Serial	2 MHz	5ms	1.7V ~ 5.5V	-40°C ~ 85°C	8-SOIC	12200
93LC66X-I/SN	Microchip	4Kbit	Microwire	2 MHz	10ms	2.5V ~ 5.5V	-40°C ~ 85°C	8-SOIC	1390
CAT93C66VI-G	onsemi	4Kbit	Microwire	2 MHz	—	1.8V ~ 5.5V	-40°C ~ 85°C	8-SOIC	2200
CAT93C66VI-GT3	onsemi	4Kbit	Microwire	2 MHz	—	1.8V ~ 5.5V	-40°C ~ 85°C	8-SOIC	24792
M93C66-RMN3TP/K	STMicroelectronics	4Kbit	Microwire	2 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 125°C	8-SOIC	15924

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications): The 93LC66/SN and 93LC66X/SN maintain identical electrical and thermal specifications to the main part. Both are ROHS3 compliant and active products. The 93LC66/SN offers higher inventory availability (2220 units) compared to the original part (980 units).

For Extended Temperature Range Applications: The 93LC66-I/SN and 93LC66X-I/SN extend operating temperature to -40°C ~ 85°C while maintaining 2.5V ~ 5.5V supply voltage and 2 MHz clock frequency. Both are ROHS3 compliant and active products with verified programmability status.

For Enhanced Performance Requirements: The 93LC66C-I/SN provides 3 MHz clock frequency and 6ms write cycle time with extended temperature range (-40°C ~ 85°C). This part offers the highest inventory availability (16166 units) among Microchip Microwire variants and is ROHS3 compliant with verified programmability.

For Lower Supply Voltage Applications: The 93AA66/SN and 93AA66C-I/SN support 1.8V minimum supply voltage compared to 2.5V for the main part. The 93AA66C-I/SN additionally provides 3 MHz operation and extended temperature range.

For Cross-Manufacturer Sourcing: The CAT93C66VI-GT3 (onsemi) offers the highest inventory availability (24792 units) with extended temperature range and 1.8V ~ 5.5V supply voltage. The M93C66-RMN3TP/K (STMicroelectronics) provides automotive-grade qualification (AEC-Q100) with extended temperature to -40°C ~ 125°C and 5ms write cycle time.

For Alternative Interface Protocol: The AT93C66B-SSHM-B implements 3-Wire Serial interface instead of Microwire, with 5ms write cycle time and extended temperature range. This part requires interface protocol compatibility verification in the target application.

Frequently Asked Questions (FAQ)

Q: Can 93AA66/SN be used as a direct replacement for 93LC66X/SN?

A: The 93AA66/SN is functionally compatible for Microwire interface applications. It maintains identical 4Kbit memory size, 512 x 8 / 256 x 16 organization, 2 MHz clock frequency, and 8-SOIC package. The primary difference is extended supply voltage range (1.8V ~ 5.5V vs. 2.5V ~ 5.5V). If your application operates at 2.5V or higher, this part is a direct substitute. Verify MSL rating (3 vs. 1) for moisture-sensitive environments.

Q: What is the difference between Microwire and 3-Wire Serial interfaces?

A: Microwire and 3-Wire Serial are distinct serial communication protocols. The 93LC66X/SN uses Microwire protocol, while the AT93C66B-SSHM-B uses 3-Wire Serial. These protocols are not interchangeable without firmware or hardware modifications. Confirm your application's interface requirements before substitution.

Q: Why would I choose 93LC66C-I/SN over 93LC66X/SN?

A: The 93LC66C-I/SN offers three advantages: 3 MHz clock frequency (vs. 2 MHz), 6ms write cycle time (vs. 10ms), and extended operating temperature range (-40°C ~ 85°C vs. 0°C ~ 70°C). Select this part for applications requiring faster write operations or operation in extended temperature environments. Inventory availability is significantly higher (16166 units).

Q: Are onsemi CAT93C66VI parts compatible with Microchip 93LC66X/SN?

A: Yes, onsemi CAT93C66VI-G and CAT93C66VI-GT3 are compatible substitutes. Both maintain 4Kbit capacity, Microwire interface, 2 MHz clock frequency, and 8-SOIC package. The primary differences are packaging format (Tube vs. Tape & Reel) and supply voltage range (1.8V ~ 5.5V). The GT3 variant offers significantly higher inventory (24792 units).

Q: What does AEC-Q100 qualification mean for the M93C66-RMN3TP/K?

A: AEC-Q100 is an automotive-grade qualification standard. The M93C66-RMN3TP/K meets automotive reliability and quality requirements with extended temperature range (-40°C ~ 125°C). Select this part for automotive applications or environments requiring automotive-grade component certification.

Q: Can I use a lower voltage part (1.8V minimum) in a 2.5V application?

A: Yes. Parts with 1.8V ~ 5.5V supply range (93AA66/SN, 93AA66C-I/SN, CAT93C66VI variants, M93C66-RMN3TP/K) are fully compatible in 2.5V applications. The lower minimum voltage specification provides additional design flexibility without compromising performance at 2.5V operation.

Q: What is the significance of MSL (Moisture Sensitivity Level) rating?

A: MSL rating indicates moisture sensitivity for surface mount components. MSL 1 (Unlimited) parts have no moisture exposure time restrictions. MSL 3 (168 Hours) parts require baking before reflow if exposed to moisture for more than 168 hours. For standard manufacturing environments, both ratings are acceptable. High-humidity or long-storage applications may require MSL 1 parts.

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