FM93CS56LM8 Equivalent & Substitute Parts

Part Overview

The FM93CS56LM8 is a 2Kbit EEPROM memory IC manufactured by onsemi, featuring Microwire serial interface protocol and 8-SOIC surface mount packaging. This component is classified as obsolete, which necessitates identification of functionally equivalent alternatives for ongoing design support and production continuity. The part operates across a 2.7V to 5.5V supply voltage range with a 250 kHz clock frequency and 15ms write cycle time.

Key Parameters

Parameter	Value
Memory Type	Non-Volatile EEPROM
Memory Size	2Kbit
Memory Organization	128 x 16
Memory Interface	Microwire
Clock Frequency	250 kHz
Write Cycle Time	15ms
Voltage Supply Range	2.7V ~ 5.5V
Operating Temperature	0°C ~ 70°C
Package Type	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitute parts for the FM93CS56LM8 are identified based on the following critical parameters that determine functional equivalence:

Core Compatibility Criteria:

Memory capacity: 2Kbit (128 x 16 organization)
Package type: 8-SOIC surface mount form factor
Supply voltage overlap: Minimum 2.7V support
Non-volatile EEPROM technology

Interface Consideration: The FM93CS56LM8 uses Microwire serial interface. Substitute parts may employ either Microwire or SPI interface protocols. SPI-based alternatives (M93S56-WMN6P, M93S56-WMN6TP) require interface protocol adaptation in circuit design but maintain electrical and mechanical compatibility.

Identified Substitute Groups:

Microwire Interface Match: 93LC56B-I/SN (Microchip Technology) — Direct protocol compatibility with Microwire interface
SPI Interface Alternatives: M93S56-WMN6P and M93S56-WMN6TP (STMicroelectronics) — Same memory capacity and package, SPI protocol requires design modification

Parameter Comparison

Parameter	FM93CS56LM8 (onsemi)	93LC56B-I/SN (Microchip)	M93S56-WMN6P (STMicroelectronics)	M93S56-WMN6TP (STMicroelectronics)
Memory Size	2Kbit	2Kbit	2Kbit	2Kbit
Memory Organization	128 x 16	128 x 16	128 x 16	128 x 16
Memory Interface	Microwire	Microwire	SPI	SPI
Clock Frequency	250 kHz	2 MHz	2 MHz	2 MHz
Write Cycle Time	15ms	6ms	5ms	5ms
Voltage Supply Range	2.7V ~ 5.5V	2.5V ~ 5.5V	2.5V ~ 5.5V	2.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Package Type	8-SOIC	8-SOIC	8-SOIC	8-SOIC
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Product Status	Obsolete	Active	Active	Active
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Protocol Compatibility: The 93LC56B-I/SN (Microchip Technology) provides the closest functional match, maintaining Microwire interface protocol compatibility while offering active product status and ROHS3 compliance. This part supports an extended operating temperature range (-40°C to 85°C) and faster write cycle time (6ms versus 15ms), representing a performance improvement over the obsolete FM93CS56LM8.

For Extended Temperature and Performance Requirements: The M93S56-WMN6P and M93S56-WMN6TP (STMicroelectronics) offer superior performance characteristics including 2 MHz clock frequency and 5ms write cycle time. These parts employ SPI interface protocol, requiring firmware and circuit-level modifications to the original Microwire implementation. Both variants are ROHS3 compliant and support the extended -40°C to 85°C temperature range. M93S56-WMN6TP is available in Cut Tape and Digi-Reel packaging formats, while M93S56-WMN6P is supplied in Tube packaging.

Compliance Consideration: All substitute parts meet ROHS3 compliance and REACH unaffected status, addressing regulatory requirements not met by the obsolete FM93CS56LM8.

Frequently Asked Questions (FAQ)

Q: Can the 93LC56B-I/SN be used as a direct replacement without circuit modification? A: Yes. The 93LC56B-I/SN maintains Microwire interface protocol compatibility with the FM93CS56LM8 and uses identical 8-SOIC packaging. Pin configuration and signal timing are compatible, allowing direct substitution without firmware changes.

Q: What design changes are required to use M93S56-WMN6P or M93S56-WMN6TP? A: These parts employ SPI serial interface protocol instead of Microwire. Circuit-level modifications to the serial communication interface and firmware updates to the microcontroller or FPGA handling memory access are required. Pin assignments differ from the original FM93CS56LM8.

Q: Are all substitute parts available in the same 8-SOIC package? A: Yes. All identified substitutes use 8-SOIC (0.154", 3.90mm Width) surface mount packaging, maintaining mechanical compatibility with the original PCB layout.

Q: What is the voltage compatibility range across all parts? A: The FM93CS56LM8 operates at 2.7V to 5.5V. All substitute parts support 2.5V to 5.5V, providing full overlap at the upper range. Designs operating below 2.7V require verification against the 2.5V minimum of substitute parts.

Q: Which substitute part offers the best performance improvement? A: The M93S56-WMN6P and M93S56-WMN6TP provide the fastest write cycle time (5ms versus 15ms) and highest clock frequency (2 MHz versus 250 kHz). Performance gains require SPI protocol implementation.

Q: Are there temperature range considerations for substitute selection? A: The FM93CS56LM8 operates at 0°C to 70°C. All substitute parts support -40°C to 85°C, providing extended temperature capability suitable for industrial and automotive applications.

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