Equivalent & Substitute Parts for 93LC66BT/ST

Part Overview

The 93LC66BT/ST is a 4Kbit EEPROM memory IC manufactured by Microchip Technology, featuring Microwire serial interface protocol and 2 MHz clock frequency in an 8-TSSOP surface mount package. This part is classified as obsolete, making substitute components necessary for new designs and ongoing production requirements. The device operates across a 2.5V to 5.5V supply voltage range with standard industrial temperature specifications of 0°C to 70°C.

Key Parameters

Parameter	Value
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
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the 93LC66BT/ST is determined by the following critical parameters: memory capacity (4Kbit), memory organization (256 x 16), serial interface protocol (Microwire), clock frequency (2 MHz), and physical package format (8-TSSOP). All substitute parts must maintain these core specifications to ensure functional compatibility within existing circuit designs.

Secondary considerations include voltage supply range compatibility, operating temperature range, write cycle time performance, and regulatory compliance certifications (RoHS3, REACH). Parts with extended temperature ranges or lower minimum voltage specifications provide enhanced operational flexibility but remain functionally interchangeable when these parameters fall within or exceed the original design requirements.

Parameter Comparison

Part Number	Manufacturer	Memory Size	Memory Organization	Interface	Clock Frequency	Write Cycle Time	Voltage Supply	Operating Temperature	Package	Product Status
93LC66BT/ST	Microchip Technology	4Kbit	256 x 16	Microwire	2 MHz	6ms	2.5V ~ 5.5V	0°C ~ 70°C	8-TSSOP	Obsolete
93LC66B/ST	Microchip Technology	4Kbit	256 x 16	Microwire	2 MHz	6ms	2.5V ~ 5.5V	0°C ~ 70°C	8-TSSOP	Active
93LC66BT-E/ST	Microchip Technology	4Kbit	256 x 16	Microwire	2 MHz	6ms	2.5V ~ 5.5V	-40°C ~ 125°C	8-TSSOP	Active
93LC66BT-I/ST	Microchip Technology	4Kbit	256 x 16	Microwire	2 MHz	6ms	2.5V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	Active
93AA66BT-I/ST	Microchip Technology	4Kbit	256 x 16	Microwire	2 MHz	6ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	Active
BR93L66RFVT-WE2	Rohm Semiconductor	4Kbit	256 x 16	Microwire	2 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	Active
BR93L66FVT-WE2	Rohm Semiconductor	4Kbit	256 x 16	Microwire	2 MHz	5ms	1.8V ~ 5.5V	-40°C ~ 85°C	8-TSSOP	Active

Engineering Selection Recommendations

Direct Replacement (Microchip Technology): The 93LC66B/ST provides the most straightforward substitution path, maintaining identical electrical specifications and operating parameters while offering active product status and higher inventory availability (4090 units). This part is suitable for applications requiring no design modifications.

Extended Temperature Range: The 93LC66BT-E/ST extends the upper operating temperature limit to 125°C, accommodating industrial and automotive applications requiring enhanced thermal performance. This variant maintains the original voltage supply range and is actively supported by the manufacturer.

Industrial Temperature Grade: The 93LC66BT-I/ST and 93AA66BT-I/ST both provide -40°C to 85°C operating ranges with active product status. The 93AA66BT-I/ST offers additional low-voltage operation down to 1.8V, enabling compatibility with modern low-power system designs.

Cross-Manufacturer Alternative: Rohm Semiconductor's BR93L66RFVT-WE2 and BR93L66FVT-WE2 provide functionally equivalent 4Kbit Microwire EEPROM solutions with improved write cycle time (5ms versus 6ms) and extended voltage range (1.8V minimum). Both variants maintain 8-TSSOP packaging and active product status.

Frequently Asked Questions (FAQ)

Q: Can 93LC66BT/ST be directly replaced with 93LC66B/ST? A: Yes. Both parts share identical memory capacity, organization, interface protocol, clock frequency, voltage supply range, and package format. The primary difference is product status; 93LC66B/ST is active while 93LC66BT/ST is obsolete.

Q: What is the difference between Microchip and Rohm substitute options? A: Microchip variants (93LC66 series) and Rohm variants (BR93L66 series) maintain equivalent 4Kbit capacity, 256 x 16 organization, Microwire interface, and 2 MHz operation. Rohm parts feature 5ms write cycle time versus 6ms for Microchip, and support lower minimum voltage (1.8V). Both manufacturers provide ROHS3 compliance and REACH compliance.

Q: Are there temperature range considerations for substitution? A: The original 93LC66BT/ST operates 0°C to 70°C. Substitute parts offer three temperature grades: standard (0°C to 70°C), industrial (-40°C to 85°C), and extended (-40°C to 125°C). Selection depends on application thermal requirements; higher-grade parts are backward compatible with lower-temperature specifications.

Q: Does voltage supply range affect substitution compatibility? A: The original part operates 2.5V to 5.5V. Substitutes with 1.8V minimum voltage (93AA66BT-I/ST, BR93L66RFVT-WE2, BR93L66FVT-WE2) provide extended low-voltage capability and remain compatible with 2.5V to 5.5V designs. Parts with 2.5V minimum voltage maintain identical voltage compatibility.

Q: What packaging options are available for substitutes? A: All substitute parts maintain 8-TSSOP surface mount packaging. Packaging variants (Tube, Tape & Reel, Cut Tape, Digi-Reel) affect supply chain logistics but do not alter electrical or mechanical compatibility.

Q: Are all substitutes RoHS3 and REACH compliant? A: Yes. All listed substitute parts maintain ROHS3 compliance and REACH unaffected status, matching the regulatory certifications of the original 93LC66BT/ST.

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