This post explores the history of Serial EEPROM part naming and explains why our massive memory product catalog should be important to you.
A Brief History of Serial EEPROM Part Nomenclature
One of the common questions we receive about our Serial EEPROM products is “Why does Microchip have so many different part numbers?”. At the time of writing this post, pulling up 1 Kbit Serial I2C EEPROMs in our parametric search tool returns 18 different product families! While this can be confusing to customers, this is the price we pay for our “No Obsolescence Policy.” In this blog post, we will talk about how we ended up here and why our massive memory product catalog should be important to you.
One of the key differentiators that sets our Serial EEPROMs apart from our competitors’ is our dedication to long product life cycles. Supply assurance is a hot topic right now as the semiconductor supply chain caused many companies to go through serious pain during the “super cycle” of 2021-2022. Companies are also thinking about geopolitical risk more than ever, with even the U.S. government taking actions through the CHIPS Act to mitigate offshoring risk of semiconductor manufacturing. Nowadays we regularly receive questions such as: How many years until End of Life (EOL)? Where are your parts manufactured? What’s the country of origin? What’s your business continuity plan? Well, the good news is that Microchip has a proven track record of long product lifecycles. We believe this is an important attribute that sets us apart in the end markets we play in like automotive, industrial, medical and defense where 10, 15 or 20 year product lifecycles are the norm. Our customers do not want to dedicate resources toward re-designing mature products. Instead, our long product life cycles enable them to focus on investing in new designs, which allows them to innovate and grow. These industries tend to have strict qualification requirements, where any EOL can be very costly as that means going through re-qualifications in addition to re-designs. That’s why we do everything in our power to continue supporting legacy products, even when newer and more cost-effective devices become available. In the case of Serial EEPROMs, we have three Microchip owned, U.S. based wafer fabs—one in Oregon, one in Arizona and one in Colorado. This checks all the boxes customers are looking for—geographic redundancy, domestic supply, flexible capacity and all completely within our control. Let’s look at some of those 1Kbit EEPROMs to see the results.
The oldest 1Kbit you will find on the Microchip website today is the 24C01C. This product harkens back to the early 90s. The number 24 was and is to this day industry standard to mean an EEPROM with I2C bus communication. The “C” at the time stood for CMOS or Complementary Metal-Oxide Semiconductor, which was still something to brag about in the 90s as CMOS technology was celebrated for its low power consumption. The “24C” products only supported 5V operating voltages, which was common operating voltage at the time for embedded systems. However, that would not last as advancements in process geometry led to lower operating voltages.
It’s estimated that in 1994, just 31% of households had computers and the Internet only had an estimated 11 million users. It wasn’t until 1996 that the www.microchip.com website began. In the semiconductor industry, product information and datasheets were being shared through “Data Books.” I happen to have a copy of the Microchip “Non-Volatile Memory Products Data Book” from 1995 as seen in Figure 1.
Figure 1: The Microchip Non-Volatile Memory Products Data Book of 1995/1996
Figure 2: The 24LC01B as seen in the 1995/1996 Data Book. This product is still available from Microchip today.
A few years after the “24C” family, Microchip had a new 1Kbit EEPROM on a new process that now supported 2.5V-5.5V which needed a name. That resulted in the 24LC01B, where the L in LC was anecdotally selected to represent “Low” as in low voltage. The trend would continue with advancements in technology leading to better performance of the memory devices. Operating voltage expanded down to 1.7V which resulted in the creation of the “24AA” series. These lower voltages were to facilitate battery powered applications and so the series was named after the common household AA battery. Bus speed later increased to 1MHz, which resulted in the “24FC” series, in which the “F” stood for “Fast.” As you can see, we have been working our way through the alphabet, loosely trying to assign meaning to our madness!
To complicate our memory portfolio even further, we acquired Atmel Semiconductor in 2016, a competing supplier of Serial EEPROMs. At integration, our memory division immediately brought Atmel’s product line under the “no obsolescence strategy” umbrella. And so, Atmel 1Kbit Serial EEPROMs like the AT24C01C and AT24C01D remain available to this day, eight years after acquisition, with no plan for EOL on the horizon.
Today, advancements in Serial EEPROMs continue with the introduction of software write protection, high speed 3.4MHz bus operation, error correction, lockable ID pages and more. This latest generation of Serial EEPROMs uses the nomenclature “24CS.” Today we have released the following advanced feature set products: 24CS256, 24CS512, 24CSM01, 25CSM04 and 25CS640 with more densities coming soon. I hope this brief history lesson was able to give you a better understanding of Microchip memory part numbers and that now you recognize that too many part options are the price we pay for product longevity. For more information on Microchip memory products, visit our memory web page.
Grant Floyd, Jul 2, 2024
Tags/Keywords: Consumer, Industrial and IoT
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