• Innovative Bus Types: Single-wire and UNI/O^® bus for pin-constrained applications and accessory authentication
• Industry-Standard Bus Types: I²C, SPI and Microwire
• Complete Product Line: Full range of densities from 128 bits to 4 Mbit to scale with your design
• Long product life cycles: Our practice of customer-driven obsolescence removes the risk of forced redesigns
• Extended Temperature and Voltage Ranges: Operation from -40°C to 150°C and 1.5V to 5.5V for industrial and automotive applications
• Reliability: Endurance of one million erase/write cycles and over 200 years of data retention
• Quality: QS9000 compliant, ISO/TS16949 compliant, AEC-Q100 compliant, RoHS compliant, Pb-free

Our serial EEPROM products are compatible with five serial bus types and support densities that range from 128 bits up to 4 Mbits. These bus types include the standard two-wire I²C, three-wire Microwire, four-wire SPI, along with proprietary single-wire and UNI/O buses. Almost all applications can be supported with operating voltages ranging from 1.5V up to 5.5V and operating temperature ranging from -40°C to 150°C.

We continue to offer new serial EEPROM innovations.  Our single-wire devices require just one I/O pin to interface with a microcontroller or another single-wire chip. These are ideal for adding verification, usage record and counterfeit protection to your devices. Additionally, we offer a family of MAC address chips, each of which is pre-programmed with unique EUI-48™ and EUI-64™ node addresses. We also manufacture Unique ID EEPROMs that are pre-programmed with a 32-, 48-, 64- or 128-bit serial number to provide device identification and tracking.

When choosing a serial EEPROM, there is a balancing act between cost and density, but the system software will usually drive this requirement. Usually the amount of memory required to complete a project is estimated before the design is completed. The final density purchased is usually 50% larger to allow for future growth.

To better illustrate the process of selecting a specific EEPROM device, here is an example of the types of questions that come up in the design phase:

• Does the microcontroller have a programmable serial port that can support I²C, SPI, Microwire or UNI/O^® serial buses?
• How many spare I/O ports on the microcontroller are available for use by the EEPROM?
  • Is your microcontroller pin limited?
  • Is it cheaper to switch to a bigger microcontroller or reduce the I/O ports required to interface with the serial EEPROM?
  • Do you need to use less I/O pins with memory on the microcontroller to free up the extra I/O pins for other applications?
• Are there any other peripherals in the system design that use a serial interface such as I²C, SPI or Microwire?
  • If no serial ports are available, will the serial interface be emulated by bit banging several I/O ports?
• How much memory will be required to complete the project and will it be necessary to upgrade to a larger memory size in the future?
  • If more memory is needed, will a larger package impact the design?
  • If more memory is needed will cascading serial EEPROMs be a viable option
• Is the bus speed known so that a bus type can be selected?
• If there is a limitation of I/O ports, will the slower speeds of the I²C or UNI/O bus meet the system requirements since they use the fewest I/O ports, two and one respectively?
• Are there any space constraints in the application that dictate a smaller package or die/wafer?
• Is there a minimum or maximum voltage or operating temperature requirement?
  

In many cases, the application notes and technical briefs you read will point you directly to the part you should use. Finally, contact your local Microchip Sales Office and discuss your findings with one of our knowledgeable sales staff or Field Applications Engineers (FAEs). They would be happy to help you with your Serial EEPROM selection.