AT93C66-10SC EEPROM 4Kbit 3-Wire Serial Equivalent & Substitute Parts

Part Overview

The AT93C66-10SC is a 4Kbit non-volatile EEPROM memory IC manufactured by Microchip Technology, featuring a 3-Wire Serial interface with 2 MHz clock frequency in an 8-SOIC surface mount package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The device operates within a 4.5V to 5.5V supply voltage range and supports standard EEPROM read/write operations with a 10ms write cycle time.

Key Parameters

Parameter	Value
Memory Size	4Kbit
Memory Organization	512 x 8, 256 x 16
Memory Interface	3-Wire Serial / Microwire
Clock Frequency	2 MHz
Write Cycle Time	10ms
Supply Voltage	4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C
Package / Case	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Part Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the AT93C66-10SC is determined by strict alignment of the following critical parameters:

Memory Capacity & Organization: All substitute parts maintain 4Kbit capacity with 512 x 8 or 256 x 16 organization, ensuring functional equivalence at the memory level.

Serial Interface Compatibility: The AT93C66-10SC uses a 3-Wire Serial interface. Substitute parts employ Microwire protocol, which is electrically and functionally compatible with 3-Wire Serial implementations for this device class.

Package & Pinout: All substitutes use the 8-SOIC (0.154", 3.90mm Width) package, maintaining identical physical form factor and pin configuration for direct board-level replacement.

Clock Frequency: Substitute parts operate at 2 MHz or higher (up to 3 MHz), ensuring compatibility with designs specified for 2 MHz operation.

Supply Voltage Range: Substitute parts support extended voltage ranges (1.8V ~ 5.5V or 2.5V ~ 5.5V), all encompassing the original 4.5V ~ 5.5V specification.

Write Cycle Time: Substitute parts feature equal or faster write cycle times (5ms to 10ms), meeting or exceeding the original 10ms specification.

Parameter Comparison

Parameter	AT93C66-10SC	93AA66/SN	93AA66CT-I/SN	CAT93C66VI-G	CAT93C66VI-GT3	M93C66-RMN3TP/K	M93C66-WMN6P	M93C66-WMN6TP
Memory Size	4Kbit	4Kbit	4Kbit	4Kbit	4Kbit	4Kbit	4Kbit	4Kbit
Memory Organization	512 x 8, 256 x 16	512 x 8, 256 x 16	512 x 8, 256 x 16	512 x 8, 256 x 16	512 x 8, 256 x 16	512 x 8, 256 x 16	512 x 8, 256 x 16	512 x 8, 256 x 16
Memory Interface	3-Wire Serial	Microwire	Microwire	Microwire	Microwire	Microwire	Microwire	Microwire
Clock Frequency	2 MHz	2 MHz	3 MHz	2 MHz	2 MHz	2 MHz	2 MHz	2 MHz
Write Cycle Time	10ms	10ms	6ms	Not Specified	Not Specified	5ms	5ms	5ms
Supply Voltage	4.5V ~ 5.5V	1.8V ~ 5.5V	1.8V ~ 5.5V	1.8V ~ 5.5V	1.8V ~ 5.5V	1.8V ~ 5.5V	2.5V ~ 5.5V	2.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C	0°C ~ 70°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 125°C	-40°C ~ 85°C	-40°C ~ 85°C
Package / Case	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)	3 (168 Hours)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Primary Substitutes (Highest Compatibility):

The M93C66-WMN6TP and M93C66-RMN3TP/K from STMicroelectronics are recommended as primary substitutes. Both parts maintain full functional equivalence with faster write cycle times (5ms versus 10ms), extended operating temperature ranges, and ROHS3 compliance. The M93C66-RMN3TP/K includes AEC-Q100 automotive qualification and supports temperatures to 125°C, suitable for demanding industrial applications.

Secondary Substitutes (Extended Voltage Range):

The 93AA66CT-I/SN from Microchip Technology offers the highest clock frequency (3 MHz) and fastest write cycle time (6ms) with extended voltage support (1.8V ~ 5.5V). This part is recommended for designs requiring enhanced performance margins or lower supply voltage operation.

Alternative Substitutes (Packaging Variants):

The CAT93C66VI-G and CAT93C66VI-GT3 from onsemi provide equivalent functionality with extended temperature ranges (-40°C ~ 85°C). These parts are available in different packaging formats (Tube and Tape & Reel) to accommodate various procurement and assembly workflows.

Compliance Considerations:

All substitute parts are ROHS3 compliant, addressing environmental and regulatory requirements that the obsolete AT93C66-10SC does not meet. The original part's RoHS non-compliance may restrict its use in new designs subject to environmental regulations.

Frequently Asked Questions (FAQ)

Q: Can the AT93C66-10SC be directly replaced with any of these substitute parts?

A: Yes, all listed substitute parts are pin-compatible and functionally equivalent. The 8-SOIC package, pinout, memory capacity, and serial interface protocol (3-Wire Serial to Microwire) are compatible for direct board-level replacement without design modification.

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

A: Both protocols are electrically and functionally compatible for this device class. Microwire is the industry-standard designation for the 3-Wire Serial protocol used in EEPROM devices. Substitute parts using Microwire protocol operate identically to the original 3-Wire Serial implementation.

Q: Which substitute part should I select for new designs?

A: For new designs, select based on application requirements: M93C66-WMN6TP for standard industrial applications, M93C66-RMN3TP/K for automotive or extended temperature environments, or 93AA66CT-I/SN for maximum performance margin. All are ROHS3 compliant and actively produced.

Q: Are there supply voltage compatibility concerns?

A: The original AT93C66-10SC requires 4.5V ~ 5.5V. All substitute parts support this range. Substitutes with extended lower voltage limits (1.8V ~ 5.5V or 2.5V ~ 5.5V) provide additional design flexibility without requiring circuit modification.

Q: What is the impact of faster write cycle times in substitute parts?

A: Substitute parts with 5ms or 6ms write cycle times (versus 10ms original) are fully backward compatible. Designs specified for 10ms write cycles operate correctly with faster parts. No firmware or timing adjustments are required.

Q: Do I need to consider Moisture Sensitivity Level (MSL) for component storage?

A: The original part has MSL 1 (unlimited shelf life). The 93AA66/SN has MSL 3 (168 hours), requiring controlled storage conditions. Other substitutes have MSL 1. Verify storage and handling requirements based on your selected substitute and procurement timeline.

Q: Is automotive qualification available in substitute parts?

A: Yes, the M93C66-RMN3TP/K includes AEC-Q100 automotive qualification and supports extended temperature range (-40°C ~ 125°C), suitable for automotive and harsh environment applications.

Q: What packaging options are available for these substitutes?

A: Substitutes are available in Tube, Cut Tape (CT) & Digi-Reel, and Tape & Reel (TR) packaging formats. Select based on assembly process requirements and procurement volume.

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