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STMicroelectronics’ M24xxx-U serial EEPROM family combines conventional I²C user memory with a factory-programmed, permanently locked 128-bit identifier. The ID can help a manufacturer associate a physical memory—and the product containing it—with a record for recognition and traceability, but it is an identifier, not cryptographic proof of authenticity.
What is ST’s Unique ID EEPROM?
Announced by STMicroelectronics on April 10, 2025, the family covers capacities from 32 Kbit to 2 Mbit. Each device includes ordinary rewritable EEPROM for application data and a separate 16-byte identification page containing a read-only serial number programmed at the factory. ST says the serial number is unique across its UID-family EEPROM devices. The announcement is also available in an earlier ST community post dated April 8, 2025. ST product announcement · ST community announcement · M24M01E-U datasheet
The UID gives a system a stable device-level value to read and associate with an inventory, manufacturing, service, or product record. ST presents the family as a plug-and-play way to add identification and traceability without a separate identification component. That link is useful only if the product’s firmware and backend record the UID and preserve the association as the product moves through its lifecycle.
How does the 128-bit UID work—and what does it not prove?
The 128-bit value is factory programmed and locked read-only in an identification page, so the application can read it but cannot rewrite it as a user value. An OEM can use it as a database key or inventory identifier to associate a specific EEPROM with a device record. For example, production software could read the UID during assembly and store it alongside the product’s model, build, or service history.
#1 Best Overall
- Onboard 8P chip carrier, supports AT24C256 series chips; pin power supply, on-board power display;
- Built-in pull-up resistor required for I2C communication;
- All pins lead out and are marked, the address input and the direct jumper settings for the write protect pin;
- PCB size: 36.5 x 12 x 12 mm (L x W x H)
A fixed identifier is not a cryptographic authentication mechanism. Reading a UID can help distinguish devices in a system that checks expected IDs against trusted records, but the number alone does not prove that a device is genuine or prevent an attacker from copying a visible value into another system. ST positions the family for basic identification and clone detection as an alternative to an entry-level secure element; it should not be treated as a substitute for a secure element when cryptographic challenge-response or protected credentials are required.
Which M24xxx-U part should you use?
Choose the density based on how much rewritable application data you need; the UID is the same 128-bit class of identification feature across the family. ST’s catalog lists these devices:
Rank #2
- EEPROM Memory
- EEPROM Memory
| Part | Capacity |
|---|---|
| M24C32-U | 32 Kbit |
| M24C64-U | 64 Kbit |
| M24128-U | 128 Kbit |
| M24256E-U | 256 Kbit |
| M24512E-U | 512 Kbit |
| M24M01E-U | 1 Mbit |
| M24M02E-U | 2 Mbit |
These capacities refer to the devices’ user-memory sizes; the UID resides in the identification page. Confirm the exact device datasheet and current catalog listing before designing around a specific part. ST product catalog and family page
What are the family’s voltage, temperature, package, and I²C limits?
ST specifies a 1.7 V to 5.5 V supply range, SO8N packaging, and an operating temperature range of −40 °C to +85 °C for the family. ST’s community announcement reports I²C operation at 100 kHz, 400 kHz, and 1 MHz, as well as random and sequential reads. Check the selected part’s datasheet for the applicable timing and operating conditions before setting a bus speed or board-level design. ST EEPROM selection guide · ST community announcement
Rank #3
- EEPROM Memory Chip Assortment
- 60 pcs, 6 types, 10 pcs each
- 24C02, 24C04, 24C08, 24C16, 24C32, 24C64
- 256B, 512B, 1MB, 2MB, 4MB, 8MB
- SOP-8 Package
How can the UID support traceability, repair, and sustainability?
ST describes uses spanning product recognition, manufacturing, field deployment, maintenance, and disposal. An OEM can associate a UID with test results or a product record at manufacture, then use that relationship to identify a unit during service or analyze reliability across a fleet. A consistent device identifier can also help a repair or reuse workflow retrieve the right product history rather than relying only on an externally applied label.
Those outcomes depend on the product maker’s implementation: the UID must be read, recorded, and linked to accurate lifecycle data. ST also positions the device as a way to support reuse, repair, and compliance efforts, but the EEPROM itself does not establish compliance or guarantee that a product will be repaired or reused.
Rank #4
- PaCkage ContentS：93LC66B-I/P DIP-8 (10 pieces)
What endurance and protection features does ST report?
ST’s April 10, 2025 announcement claims 4 million write cycles and 200-year data retention. These are manufacturer claims, not independent test results; treat them as specifications to verify against the relevant part datasheet and the conditions of your application. The 4 million-cycle figure concerns writes to EEPROM memory, not repeated changes to the locked UID.
The April 8, 2025 community announcement also reports whole-array write protection, enhanced ESD and latch-up protection, and 4 kV Human Body Model ESD protection. These figures and features are reported by ST; consult the selected device’s datasheet for definitions, limits, and the conditions under which they apply. ST product announcement · ST community announcement
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When is this family a good fit?
- Consider it when a design needs ordinary serial EEPROM plus a permanent device identifier for inventory, service, or product-record linkage.
- Do not rely on the UID alone when authenticity depends on cryptographic proof or protection against deliberate cloning; use a security solution designed for that threat model.
- Plan the data workflow so manufacturing and service systems read the UID and maintain its association with the physical product.
- Check the exact part for capacity, interface timing, and conditions that matter to the design rather than assuming every detail is identical across the family.
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