FM93CS56M8 EEPROM Memory IC Equivalent & Substitute Parts

Part Overview

The FM93CS56M8 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 substitute parts for new designs or production continuity. The part operates within a 4.5V to 5.5V supply voltage range with a 1 MHz clock frequency and 10ms write cycle time, serving applications requiring non-volatile serial memory storage in compact form factors.

Key Parameters

Parameter	FM93CS56M8 Specification
Memory Size	2Kbit
Memory Organization	128 x 16
Memory Interface	Microwire
Clock Frequency	1 MHz
Write Cycle Time	10ms
Voltage Supply Range	4.5V ~ 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

Substitution of the FM93CS56M8 is determined by the following critical parameters: memory capacity (2Kbit), memory organization (128 x 16), physical package (8-SOIC), and surface mount compatibility. Two substitution categories exist based on serial interface protocol:

Category 1: Microwire Interface Substitutes maintain the original Microwire protocol, ensuring direct firmware and hardware compatibility without protocol conversion. The 93C56B-E/SN from Microchip Technology qualifies as a Microwire-based substitute with identical memory specifications and package form factor.

Category 2: SPI Interface Substitutes employ Serial Peripheral Interface (SPI) protocol instead of Microwire. While these parts share identical memory capacity, organization, and packaging, they require interface protocol adaptation at the system level. The M93S56-WMN6P and M93S56-WMN6TP from STMicroelectronics represent this category, available in different packaging formats (Tube and Cut Tape/Digi-Reel respectively).

Parameter Comparison

Parameter	FM93CS56M8 (onsemi)	93C56B-E/SN (Microchip)	M93S56-WMN6P (STMicro)	M93S56-WMN6TP (STMicro)
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	1 MHz	2 MHz	2 MHz	2 MHz
Write Cycle Time	10ms	2ms	5ms	5ms
Voltage Supply Range	4.5V ~ 5.5V	4.5V ~ 5.5V	2.5V ~ 5.5V	2.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C	-40°C ~ 125°C	-40°C ~ 85°C	-40°C ~ 85°C
Package Type	8-SOIC	8-SOIC	8-SOIC	8-SOIC
Product Status	Obsolete	Active	Active	Active
RoHS Compliance	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Microwire Protocol): The 93C56B-E/SN from Microchip Technology is the primary substitute for the FM93CS56M8. This part maintains Microwire serial interface compatibility, eliminating firmware modifications. The substitute offers superior performance characteristics including doubled clock frequency (2 MHz vs. 1 MHz), reduced write cycle time (2ms vs. 10ms), and extended operating temperature range (-40°C to 125°C vs. 0°C to 70°C). The part is currently in active production status with ROHS3 compliance certification, ensuring long-term availability and regulatory alignment.

For Protocol-Adaptive Applications (SPI Interface): The M93S56-WMN6P and M93S56-WMN6TP from STMicroelectronics provide functionally equivalent 2Kbit EEPROM storage with SPI protocol implementation. These substitutes require system-level interface adaptation but deliver extended supply voltage range (2.5V to 5.5V), supporting lower-voltage applications. Both variants maintain identical electrical specifications and 8-SOIC packaging. The M93S56-WMN6TP variant, supplied in Cut Tape and Digi-Reel format, offers higher inventory availability (56,680 units) compared to the tube-packaged M93S56-WMN6P (20,200 units).

All substitute parts carry ROHS3 compliance and active product status, ensuring regulatory compliance and manufacturing continuity.

Frequently Asked Questions (FAQ)

Q: Can the 93C56B-E/SN directly replace the FM93CS56M8 without circuit modifications?

A: Yes. The 93C56B-E/SN maintains Microwire serial interface protocol and identical memory organization (128 x 16, 2Kbit). Both parts operate within the 4.5V to 5.5V supply range and use 8-SOIC surface mount packaging. No hardware or firmware modifications are required for direct substitution.

Q: What is the primary difference between Microwire and SPI interface substitutes?

A: Microwire and SPI are distinct serial communication protocols with different signal timing and control sequences. The 93C56B-E/SN uses Microwire protocol matching the original FM93CS56M8, while M93S56 variants employ SPI protocol. Direct substitution of SPI parts requires system-level interface adaptation and firmware modification to handle protocol differences.

Q: Are the STMicroelectronics M93S56-WMN6P and M93S56-WMN6TP electrically identical?

A: Yes. Both M93S56 variants are electrically identical with 2Kbit capacity, SPI interface, 2 MHz clock frequency, and 5ms write cycle time. The difference is packaging format: M93S56-WMN6P is supplied in Tube packaging, while M93S56-WMN6TP is supplied in Cut Tape and Digi-Reel format. Selection depends on production assembly requirements and inventory management preferences.

Q: Does the FM93CS56M8 operate at lower voltages than substitute parts?

A: The FM93CS56M8 requires 4.5V to 5.5V supply voltage. The 93C56B-E/SN maintains this voltage range. The STMicroelectronics M93S56 variants extend the lower voltage limit to 2.5V, enabling operation in lower-voltage systems while remaining compatible with 5V applications.

Q: What compliance certifications apply to substitute parts?

A: Both the 93C56B-E/SN and M93S56 variants carry ROHS3 compliance certification and REACH Unaffected status. The original FM93CS56M8 is RoHS non-compliant. Substitute parts meet current environmental and regulatory requirements for new product designs and manufacturing.

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