93C66C-I/ST EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The 93C66C-I/ST is a 4Kbit non-volatile EEPROM memory IC manufactured by Microchip Technology, featuring Microwire serial interface protocol and 8-TSSOP surface mount packaging. This component is classified as Active product status and is ROHS3 compliant. Substitute parts are identified when equivalent memory capacity, interface protocol, package form factor, and electrical operating ranges align with application requirements.

Key Parameters

Parameter	Specification
Memory Size	4Kbit
Memory Organization	512 x 8, 256 x 16
Memory Interface	Microwire
Clock Frequency	3 MHz
Voltage Supply Range	4.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Package / Case	8-TSSOP (0.173", 4.40mm Width)
Mounting Type	Surface Mount
Write Cycle Time	2ms

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following critical parameters:

Memory Capacity: 4Kbit (512 x 8 or 256 x 16 organization)
Serial Interface Protocol: Microwire or 3-Wire Serial
Package Form Factor: 8-TSSOP with 0.173" width and 4.40mm dimensions
Surface Mount Compatibility: All candidates must support surface mount assembly
Voltage Supply Compatibility: Operating voltage range must encompass or exceed the application requirement
Temperature Range: Operating temperature must cover -40°C to 85°C minimum

The 93C66C-I/ST operates at 3 MHz clock frequency with 4.5V to 5.5V supply voltage. Substitute parts meeting the above criteria are listed below, with variations in clock frequency, write cycle time, and supply voltage range noted for design consideration.

Parameter Comparison

Parameter	93C66C-I/ST	93LC66C-I/ST	AT93C66B-XHM-B	M93C66-RDW3TP/K	M93C66-WDW6TP
Manufacturer	Microchip Technology	Microchip Technology	Microchip Technology	STMicroelectronics	STMicroelectronics
Memory Size	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
Memory Interface	Microwire	Microwire	3-Wire Serial	Microwire	Microwire
Clock Frequency	3 MHz	3 MHz	2 MHz	2 MHz	2 MHz
Write Cycle Time	2ms	6ms	5ms	5ms	5ms
Voltage Supply Range	4.5V ~ 5.5V	2.5V ~ 5.5V	1.7V ~ 5.5V	1.8V ~ 5.5V	2.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 125°C	-40°C ~ 85°C
Package / Case	8-TSSOP	8-TSSOP	8-TSSOP	8-TSSOP	8-TSSOP
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Active	Active	Active	Active	Active

Engineering Selection Recommendations

93LC66C-I/ST (Microchip Technology): Direct Microwire interface match with identical 3 MHz clock frequency. Extended supply voltage range (2.5V ~ 5.5V) provides broader application flexibility. Write cycle time extends to 6ms compared to 2ms on the primary part. Product status Active with verified programmability. Suitable for applications where lower supply voltage operation is beneficial and extended write cycle time is acceptable.

AT93C66B-XHM-B (Microchip Technology): Implements 3-Wire Serial interface protocol instead of Microwire, requiring circuit-level interface modification. Clock frequency reduced to 2 MHz. Supply voltage range extends to 1.7V minimum. Product status Active. Selection requires confirmation of interface protocol compatibility at the system level.

M93C66-RDW3TP/K (STMicroelectronics): Microwire interface with 2 MHz clock frequency. Supply voltage range 1.8V ~ 5.5V. Operating temperature range extends to 125°C. Automotive grade qualification with AEC-Q100 certification. Tape & Reel packaging. Suitable for automotive and extended temperature applications.

M93C66-WDW6TP (STMicroelectronics): Microwire interface with 2 MHz clock frequency. Supply voltage range 2.5V ~ 5.5V. Standard operating temperature range -40°C ~ 85°C. Cut Tape & Digi-Reel packaging with highest inventory availability (105,200 pcs). Product status Active with verified programmability. Optimal for high-volume procurement and standard industrial applications.

Frequently Asked Questions (FAQ)

Q: Can 93LC66C-I/ST replace 93C66C-I/ST in all applications?

A: 93LC66C-I/ST maintains Microwire interface compatibility and identical clock frequency (3 MHz). The extended supply voltage range (2.5V ~ 5.5V) is backward compatible with the 4.5V ~ 5.5V requirement. Extended write cycle time (6ms vs 2ms) must be evaluated against timing-critical operations. Both parts use identical 8-TSSOP packaging.

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

A: AT93C66B-XHM-B implements 3-Wire Serial protocol, while 93C66C-I/ST uses Microwire protocol. These are distinct serial communication standards requiring different pin configurations and signal timing. Interface protocol selection is determined by system-level design and cannot be changed through firmware alone.

Q: Are STMicroelectronics M93C66 variants pin-compatible with Microchip 93C66C?

A: All substitute parts use identical 8-TSSOP package form factor with 0.173" width and 4.40mm dimensions. Microwire interface variants (M93C66-RDW3TP/K and M93C66-WDW6TP) maintain protocol compatibility. Pin assignment verification against specific datasheet documentation is required before board-level substitution.

Q: Which substitute part offers the widest operating temperature range?

A: M93C66-RDW3TP/K extends operating temperature to -40°C ~ 125°C, compared to -40°C ~ 85°C on the primary part and other substitutes. This variant includes automotive grade qualification and AEC-Q100 certification.

Q: What packaging options are available for substitute parts?

A: 93LC66C-I/ST and AT93C66B-XHM-B are supplied in Tube packaging. M93C66-RDW3TP/K is supplied in Tape & Reel format. M93C66-WDW6TP is supplied in Cut Tape & Digi-Reel format. Packaging selection affects procurement quantity minimums and handling requirements.

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