Microchip Releases the Largest Capacity EEPROM Chip Available to the MarketAugust 26, 2020 by Jake Hertz
This week, Microchip announced the release of a 4Mbit EEPROM chip—more than double the capacity of the previous largest on the market.
As designers are faced with designs for portable consumer electronics, medical devices, and certain automotive systems, they may look to memory for innovation. These applications tend to use customer-specific information, such as calibration constants, background conditions, user preferences, or changing noise environments.
For this, designers need a form of non-volatile memory ROM that can store small amounts of data but still be updated and manipulated as needed. The answer that many developers have turned to is what is known as electrically erasable programmable read-only memory (EEPROM).
This week, Microchip broke news that has shaken up the EEPROM market. Their newest chip, a 4Mbit EEPROM device, offers more than double the capacity of standard 2Mbit EEPROMs, making it the largest available on the market.
Just how influential is this announcement for memory designs?
EEPROM on a Lower Level
We might answer this question by first assessing the fundamental advantages of EEPROM. An EEPROM is a device where each cell consists of two transistors: 1) the storage transistor with a floating gate and 2) an access transistor, which is required for operations.
Floating gate MOS vs. conventional MOS structure. Image used courtesy of the University of Michigan
The floating gate MOS structure, very similar to conventional CMOS, is used to program data into memory. The programmed 1 or 0 logic state is dependent on the presence or absence of an electrical charge on the floating gate.
Example EEPROM signals. Image used courtesy of the University of Michigan
As its name implies, the otherwise unwritable memory of the device can be erased and subsequently rewritten by applying special electrical signals to the structure.
Serial and Parallel Access
EEPROM comes in two flavors: serial and parallel access. Serial access makes up about 90 percent of the overall EEPROM market while parallel makes up the other 10 percent.
Parallel devices are available in higher densities and are faster. They also characterized by their high endurance and reliability. This makes them useful in military applications. Serial access, on the other hand, is much slower and less dense but is significantly cheaper. For this reason, serial access is used in commercial applications.
EEPROM: What’s so Great About It?
One of the major benefits of using EEPROM is that it can be easily manipulated if needed. EEPROM also offers advantages over NOR Flash memory since NOR Flash is only rewritable in large blocks while EEPROM offers per byte erasure.
EEPROM excels in that it offers users excellent capabilities and performance. Only one external power supply is required since the high voltage for program/erase is internally generated from the floating gate.
EEPROM vs. Flash. Screenshot used courtesy of Microchip
The list of benefits continues, with EEPROM offering:
- A lower standby current: 2 μA vs. 15 μA for NOR Flash
- Shorter sector erase/rewrite times: 5ms vs.300ms
- More erase/rewrite cycles 1M vs. 100K
These benefits have made EEPROM the obvious choice for storing configuration data based on customer-centric data sets. Unfortunately, these devices have been met with a big limitation: they offer extremely low capacity. With this in mind, Microchip has been working to create the next generation of high capacity EEPROM chips.
Microchip Doubles the Capacity of Standard EEPROM
Until news of this release, Microchip explains that designers had the option of lower-cost NOR Flash ICs for "any 2 Mbit+ nonvolatile data set application." The new 4 Mbit EEPROM, however, takes the cake for the largest EEPROM available to developers, doubling the 2 Mbit density cap most designers are familiar with.
The new device, dubbed the 25CSM04, integrates within Microchip’s pre-existing total system solutions built around its 8-bit, 16-bit, and 32-bit microcontrollers and microprocessors.
Microchip's 25CSM04. Image used courtesy of Microchip
According to Randy Drwinga, VP of Microchip’s memory products division, the company is “pushing the top end of what is possible with serial EEPROM supports product innovation... Designers can now reevaluate their systems and leverage this new technology to optimize design performance.”
New Horizons for Memory
This news from Microchip suggests significant improvement in the field of EEPROM memory and could have some important implications. As devices continue to become more and more user-centric, there will definitely be a need for non-volatile, high capacity ROM.
Overcoming the drawbacks of EEPROM allows designers to reap its benefits, such as low power and bytewise re-programmability. Fields such as consumer electronics, medical devices, and many others will certainly see the repercussions of this advancement in the near future.