93C66BT-I/ST EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The 93C66BT-I/ST is a 4Kbit non-volatile EEPROM memory IC manufactured by Microchip Technology, featuring Microwire serial interface protocol and 2 MHz clock frequency. The device is packaged in 8-TSSOP surface mount configuration with supply voltage range of 4.5V to 5.5V and operating temperature range of -40°C to 85°C. This part is currently in active production status with ROHS3 compliance and unlimited moisture sensitivity level (MSL 1).

Equivalent and substitute parts are necessary when the original packaging format (Tape & Reel) is unavailable, when alternative voltage specifications are required for specific applications, or when sourcing from alternative manufacturers becomes necessary for supply chain optimization.

Key Parameters

Parameter	Specification
Memory Size	4Kbit
Memory Organization	256 x 16
Memory Interface	Microwire
Clock Frequency	2 MHz
Voltage Supply Range	4.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Package Type	8-TSSOP (0.173", 4.40mm Width)
Mounting Type	Surface Mount
Write Cycle Time	2ms

Substitute Part Grouping Explanation

Substitution eligibility for the 93C66BT-I/ST is determined by the following critical parameters: memory size (4Kbit), memory organization (256 x 16), Microwire interface protocol, 2 MHz clock frequency, 8-TSSOP package configuration, and surface mount mounting type. These parameters define the functional and physical compatibility requirements.

The substitute parts are grouped into two categories:

Category 1: Direct Microchip Technology Substitutes — Parts maintaining identical electrical specifications with variations in packaging format only (Tube vs. Tape & Reel). The 93C66B-I/ST operates under identical voltage (4.5V ~ 5.5V) and temperature (-40°C ~ 85°C) parameters.

Category 2: Extended Specification Substitutes — Parts with compatible core memory specifications but expanded voltage or temperature ranges, or alternative manufacturers. The 93LC66BT-I/ST extends voltage compatibility to 2.5V ~ 5.5V with extended write cycle time of 6ms. The Rohm Semiconductor parts (BR93A66RFVT-WME2 and BR93L66FVT-WE2) maintain 4Kbit memory size and Microwire interface with voltage ranges of 2.5V ~ 5.5V and 1.8V ~ 5.5V respectively, with write cycle times of 5ms.

Parameter Comparison

Parameter	93C66BT-I/ST	93C66B-I/ST	93LC66BT-I/ST	BR93A66RFVT-WME2	BR93L66FVT-WE2
Manufacturer	Microchip Technology	Microchip Technology	Microchip Technology	Rohm Semiconductor	Rohm Semiconductor
Memory Size	4Kbit	4Kbit	4Kbit	4Kbit	4Kbit
Memory Organization	256 x 16	256 x 16	256 x 16	256 x 16	256 x 16
Memory Interface	Microwire	Microwire	Microwire	Microwire	Microwire
Clock Frequency	2 MHz	2 MHz	2 MHz	2 MHz	2 MHz
Voltage Supply Range	4.5V ~ 5.5V	4.5V ~ 5.5V	2.5V ~ 5.5V	2.5V ~ 5.5V	1.8V ~ 5.5V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 105°C	-40°C ~ 85°C
Write Cycle Time	2ms	2ms	6ms	5ms	5ms
Package Type	8-TSSOP	8-TSSOP	8-TSSOP	8-TSSOP	8-TSSOP
Packaging Format	Tape & Reel (TR)	Tube	Cut Tape (CT) & Digi-Reel®	Tape & Reel (TR)	Cut Tape (CT)
Product Status	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

93C66B-I/ST — Direct substitute for identical electrical specifications with Tube packaging. Suitable for applications where Tape & Reel format is not required. All compliance certifications and product status match the original part.

93LC66BT-I/ST — Recommended for applications requiring extended lower voltage operation down to 2.5V. Microchip Technology manufacturer continuity is maintained. DiGi-Electronics Programmable verification is confirmed. Extended write cycle time of 6ms must be evaluated against application timing requirements. Available in Cut Tape and Digi-Reel packaging formats.

BR93A66RFVT-WME2 — Rohm Semiconductor alternative with extended operating temperature range to 105°C and automotive-grade qualification (AEC-Q100). Suitable for automotive and high-temperature applications. Extended voltage range to 2.5V minimum. Write cycle time of 5ms. Tape & Reel packaging available.

BR93L66FVT-WE2 — Rohm Semiconductor alternative with lowest voltage specification (1.8V minimum) for ultra-low-power applications. DiGi-Electronics Programmable verification confirmed. Write cycle time of 5ms. Cut Tape packaging format.

Frequently Asked Questions (FAQ)

Q: Can 93C66B-I/ST replace 93C66BT-I/ST in production? A: Yes. Both parts maintain identical electrical specifications (4Kbit, 256 x 16 organization, Microwire interface, 2 MHz clock, 4.5V ~ 5.5V supply, -40°C ~ 85°C operating range, 2ms write cycle time). The difference is packaging format: 93C66B-I/ST uses Tube packaging while 93C66BT-I/ST uses Tape & Reel. Substitution is valid when packaging format compatibility is confirmed.

Q: What is the primary difference between 93LC66BT-I/ST and 93C66BT-I/ST? A: The 93LC66BT-I/ST extends the minimum supply voltage from 4.5V to 2.5V, enabling operation in lower-voltage applications. The write cycle time increases from 2ms to 6ms. All other parameters including memory size, interface protocol, clock frequency, and operating temperature remain identical.

Q: Are Rohm Semiconductor parts (BR93A66RFVT-WME2 and BR93L66FVT-WE2) pin-compatible with Microchip parts? A: Yes. Both manufacturers maintain the 8-TSSOP package configuration with identical pinout for Microwire interface protocol. Physical and electrical pin compatibility is maintained across all substitute parts listed.

Q: Which substitute part is suitable for automotive applications? A: BR93A66RFVT-WME2 is qualified for automotive use with AEC-Q100 certification and extended operating temperature range to 105°C. This part is specified for automotive-grade applications.

Q: What is the impact of extended write cycle time on system design? A: Write cycle time determines the duration required to complete a single word or page write operation. The 93LC66BT-I/ST (6ms) and Rohm parts (5ms) have longer write cycles than the original 93C66BT-I/ST (2ms). Applications with time-critical write operations must evaluate whether extended write cycle time affects system performance or timing requirements.

Q: Are all substitute parts ROHS3 compliant? A: Yes. All listed substitute parts maintain ROHS3 compliance status identical to the original 93C66BT-I/ST.

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