ST has been the leading manufacturer of EEPROM for the 20th consecutive year. As we celebrate this milestone, we wanted to reflect on why the electrically erasable programmable read-only memory market remains strong, the problems it solves, why it still plays a critical role in many designs, and where we go from here. Indeed, despite the rise in popularity of Flash, SRAM, and other new memory types, EEPROM continues to meet the needs of engineers seeking a compact, reliable memory. In fact, over the last 20 years, we have seen ST customers try to migrate away from EEPROM only to return to it with even greater fervour.
Why companies choose EEPROM today?
Granularity
One of the main advantages of electrically erasable programmable read-only memory is its byte-level granularity. Whereas writing to other memory types, like flash, means erasing an entire sector, which can range from many bytes to hundreds of kilobytes, depending on the model, an EEPROM is writable byte by byte. This is tremendously beneficial when writing logs, sensor data, settings, and more, as it saves time, energy, and reduces complexity, since the writing operation requires fewer steps and no buffer. For instance, using an EEPROM can save significant resources and speed up manufacturing when updating a calibration table on the assembly line.
Performance
The very nature of EEPROM also gives it a significant endurance advantage. Whereas flash can only support read/write cycles in the hundreds of thousands, an EEPROM supports millions, and its data retention is in the hundreds of years, which is crucial when dealing with systems with a long lifespan. Similarly, its low peak current of a few milliamps and its fast boot time of 30 µs mean it can meet the most stringent low-power requirements. Additionally, it enables engineers to store and retrieve data outside the main storage. Hence, if teams are experiencing an issue with the microcontroller, they can extract information from the EEPROM, which provides additional layers of safety.
Convenience
These unique abilities explain why automotive, industrial, and many other applications just can’t give up EEPROM. For many, giving it up could break software implementation or require a significant redesign. Indeed, one of the main advantages of EEPROM is that they fit into a small 8-pin package regardless of memory density (from 1 Kbit to 32 Mbit). Additionally, they tolerate high operating temperatures of up to 145 °C for serial EEPROM, making them easy to use in a wide range of environments. The middleware governing their operations is also significantly more straightforward to write and maintain, given their operation.
Resilience
Since ST controls the entire manufacturing process, we can provide greater guarantees to customers facing supply chain uncertainties. Concretely, ST offers EEPROM customers a guarantee of supply availability through our longevity commitment program (10 years for industrial-grade products, 15 years for automotive-grade). This explains why, 40 years after EEPROM development began in 1985 and after two decades of leadership, some sectors continue to rely heavily on our EEPROMs. And why new customers seeking a stable long-term data storage solution are adopting it, bolstered by ST’s continuous innovations, enabling new use cases.
Why will the industry need EEPROM tomorrow?
More storage
Since its inception in the late 70s, EEPROM’s storage has always been relatively minimal. In many instances, it is a positive feature for engineers who want to reserve their EEPROM for small, specific operations and segregate it from the rest of their storage pool. However, as serial EEPROM reached 4 Mbit and 110 nm, the industry wondered whether the memory could continue to grow in capacity while shrinking process nodes. A paper published in 2004 initially concluded that traditional EEPROMs “scale poorly with technology”. Yet, ST recently released a Page EEPROM capable of storing 32 Mbit that fits inside a tiny 8-pin package.
The Page EEPROM adopts a hybrid architecture, meaning it uses 16-byte words and 512-byte pages while retaining the ability to write at the byte level. This offers customers the flexibility and robustness of traditional EEPROM but bypasses some of the physical limitations of serial EEPROM, thus increasing storage and continuing to serve designs that rely on this type of memory while still improving endurance. Indeed, a Page EEPROM supports a cumulative one billion cycles across its entire memory capacity. For many, Page EEPROMs represent a technological breakthrough by significantly expanding data storage without changing the 8-pin package size. That’s why we’ve seen them in asset tracking applications and other IoT applications that run on batteries.
New features
ST also recently released a Unique ID serial EEPROM, which uses the inherent capabilities of electrically erasable programmable read-only memory to store a unique ID or serial number to trace a product throughout its assembly and life cycle. Usually, this would require additional components to ensure that the serial number cannot be changed or erased. However, thanks to its byte-level granularity and read-only approach, the new Unique ID EEPROM can store this serial number while preventing any changes, thus offering the benefits of a secure element while significantly reducing the bill of materials. Put simply, the future of EEPROM takes the shape of growing storage and new features.
