FM93C66EN EEPROM 4Kbit Microwire Equivalent & Substitute Parts

Part Overview

The FM93C66EN is a 4Kbit EEPROM memory IC manufactured by onsemi, featuring Microwire serial interface protocol and 8-DIP through-hole packaging. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing system maintenance, legacy device repairs, and production continuity. The part operates at 1 MHz clock frequency with 10ms write cycle time and requires 4.5V to 5.5V supply voltage across an industrial temperature range of -40°C to 85°C.

Substiute Parts

FM93C66EN

onsemiIn Stock: 1135FM93C66EN Datasheet

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93C66A-E/P

Microchip TechnologyIn Stock: 90993C66A-E/P Datasheet

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93C66B-E/P

Microchip TechnologyIn Stock: 70193C66B-E/P Datasheet

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93C66B-I/P

Microchip TechnologyIn Stock: 771093C66B-I/P Datasheet

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93LC66B-I/P

Microchip TechnologyIn Stock: 1962893LC66B-I/P Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the FM93C66EN is determined by the following critical parameters: 4Kbit memory capacity, EEPROM non-volatile memory format, Microwire serial interface protocol, 8-DIP through-hole package, and compatible voltage supply range. All qualified substitute parts maintain these core specifications. Secondary parameters including clock frequency, write cycle time, memory organization, operating temperature range, and product status are documented to enable informed selection based on application requirements and compliance needs.

Parameter Comparison

Engineering Selection Recommendations

All four substitute parts (93C66A-E/P, 93C66B-E/P, 93C66B-I/P, and 93LC66B-I/P) are manufactured by Microchip Technology and maintain active product status, ensuring long-term availability and supply chain reliability. All substitutes are ROHS3 compliant, addressing environmental and regulatory requirements that the obsolete FM93C66EN does not meet.

For applications requiring extended temperature operation beyond 85°C, the 93C66A-E/P and 93C66B-E/P support -40°C to 125°C operating range. For applications with reduced supply voltage requirements, the 93LC66B-I/P operates across 2.5V to 5.5V, providing greater flexibility in power supply design.

The 93C66B-I/P and 93LC66B-I/P are recommended as primary substitutes due to matching -40°C to 85°C temperature specifications and highest inventory availability (7,627 and 19,527 units respectively). The 93C66A-E/P and 93C66B-E/P offer enhanced performance characteristics with 2 MHz clock frequency and faster write cycles, suitable for applications where improved speed is beneficial.

Frequently Asked Questions (FAQ)

Q: Can the 93LC66B-I/P replace the FM93C66EN in all applications?

A: The 93LC66B-I/P is functionally compatible as a direct substitute. It maintains 4Kbit capacity, Microwire interface, 8-DIP package, and -40°C to 85°C operating temperature. The extended voltage range (2.5V to 5.5V versus 4.5V to 5.5V) provides additional design flexibility. Verify that your application's supply voltage and clock frequency requirements are compatible with the 2 MHz specification.

Q: What is the difference between 93C66B-E/P and 93C66B-I/P?

A: Both parts are identical in electrical specifications and package type. The primary difference is operating temperature range: 93C66B-E/P operates -40°C to 125°C, while 93C66B-I/P operates -40°C to 85°C. Select based on your application's thermal environment requirements.

Q: Are all substitute parts RoHS compliant?

A: Yes. All four substitute parts (93C66A-E/P, 93C66B-E/P, 93C66B-I/P, and 93LC66B-I/P) are ROHS3 compliant. The original FM93C66EN is RoHS non-compliant, making substitution necessary for applications requiring environmental compliance.

Q: Does the 2 MHz clock frequency of substitute parts affect compatibility?

A: The substitute parts operate at 2 MHz clock frequency compared to the FM93C66EN's 1 MHz. This higher frequency is backward compatible with 1 MHz applications. Verify that your circuit design and firmware support the faster clock speed if timing-critical operations are present.

Q: What is the inventory status of these substitute parts?

A: All substitute parts are in active production with substantial inventory: 93C66A-E/P (892 units), 93C66B-E/P (616 units), 93C66B-I/P (7,627 units), and 93LC66B-I/P (19,527 units). The 93LC66B-I/P offers the highest availability for immediate procurement.