Microchip logo
  • All
  • Products
  • Documents
  • Applications Notes
microchip serial eeprom memory diagram
Step 1: Microchip’s Serial EEPROM Overview
Serial EEPROMs

Microchip’s Serial EEPROM products are compatible with four serial bus types and support densities that range from 128 bits up to 1 Mbits. These bus types include the standard two wire I2C, three-wire Microwire, four wire SPI and the new single I/O, UNI/O® bus. As Microchip’s EEPROMs are compatible with the de facto industry standards, they can be used as drop-in replacements for competitor devices in most cases. By supporting a wide operating voltage range from 1.7 volts up to 5.5 volts and a wide temperature range from -40°C to 125°C almost all applications are supported. For new designs, Microchip's value-added features include smaller footprints, lower power consumption, lower voltage levels (down to 1.5V), faster bus rates and higher endurance levels help ensure truly robust designs of the highest quality.

Microchip has been at the forefront of Serial EEPROM innovation - Along with ensuring highest quality products, today we offer a new family of single I/O UNI/O® EEPROM devicesthe lowest voltage EEPROMs at 1.5V, the fastest bus speed on the SPI at 20 MHz and provide the industry’s lowest operating current which ensures lower power consumption. Microchip also recently launched a family of MAC address chips each of which are pre-programmed with unique EUI-48™ and EUI-64™ node addresses.

Packages Supported

Microchip serial EEPROMs are packaged at Microchip's own facilities and by authorized subcontractors. After packaging, whether in-house or at an outside subcontractor, every device is 100% tested thrice prior to shipment. Microchip excels at micro-miniature packaging for serial EEPROMs and currently supports the following packages:

8-Lead PDIP (8x9.5)P128 bits – 1M1K-16K1K – 16K1K – 1M
8-Lead SOIC (5x6)SN128 bits – 1M1K-16K1K – 16K1K – 1M
8-Lead TSSOP (3x6.5)ST128 bits – 512KNA1K – 16K1K – 256K
8-Lead MSOP (3x5)MS128 bits – 256K1K-16K1K – 16K1K – 64K
8-Lead DFN, T-DFN (2x3)MC, MNY128 bits – 128K1K-16K1K – 16K1K – 64K
8-Lead DFN-S (5x6)MF128K – 512KNANA64K – 1M
3-Lead SOT-23 (3x3)OTNA1K-16KNANA
5-Lead SOT-23 (3x3)OT128 bits – 64KNANANA
6-Lead SOT-23 (3x3)TTNANA1K – 16K1K – 4K
5-Lead SC70 (2x2)LT1K-2KNANANA
WLCSP (~die sized)CS16K4K-512KNANANA

Click here for up to date package information. We also support all parts in wafers.

  • Standby current less than 1 uAmp and industry’s lowest operating current. (low power)
  • Erase / Write endurance levels exceeding 1 million cycles and over 200 years Data retention.
  • Low-voltage / high-frequency support with 400 KHz I2C devices at 1.7 volts.
  • Small package leader with the 2K I2C device in the 5-lead SC70, 3-lead SOT-23 on the new UNI/ bus, a 128 Kbit I2C device in the 2x3 DFN, WLCSP as well as 64 Kbit I2C device in the SOT-23.
  • Ensure highest quality by testing all devices 3 times before shipping.
  • Die and wafer support available.
  • Industry’s shortest lead times, excellent delivery
Step 2: How to Select Your Serial EEPROM

When choosing the correct EEPROM for your application, a variety of system design decisions must be taken into account. These decisions are based upon the answers to the following questions:

  • How many serial bus drivers are available on the microcontroller?
  • How many I/O ports are available on the microcontroller?
  • What are the different bus interfaces in the other system peripherals?
  • How much memory is required for the application?
  • What is the maximum speed of the serial communications bus?
  • In order to determine the best package for the application, what is the physical size available?
  • Finally, are there any specific voltage or temperature constraints?

When choosing a Serial EEPROM, there is a balancing act between cost and density, but the system software application 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.

In order to understand the process in selecting a specific EEPROM device, an example of the types of questions that come up in the design phase is shown below:

  1. Does the microcontroller have a programmable serial port that can support I2C, SPI, Microwire or UNI/O® serial buses?
  2. How many spare I/O ports on the microcontroller are available for use by the EEPROM?
    1. Is your Microcontroller pin limited?
    2. Is it cheaper to switch to a bigger microcontroller or reduce the I/O ports required to interface with the serial EEPROM?
    3. 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?
  3. Are there any other peripherals in the system design that use a serial interface such as I2C, SPI or Microwire?
    1. If no serial ports are available, will the serial interface be emulated by bit banging several I/O ports?
  4. 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?
    1. If more memory is needed, will a larger package impact the design?
    2. If more memory is needed will cascading serial EEPROMs be a viable option
  5. Is the bus speed known, so that a bus type can be selected?
  6. If there is a limitation of I/O ports, will the slower speeds of the I2C, UNI/O bus meet the system requirements, since they use the fewest I/O ports, two and one respectively?
  7. Are there any space constraints in the application that dictates a smaller package or die/wafer?
  8. Is there a minimum or maximum voltage or operating temperature requirement?

When selecting the correct Serial EEPROM, the most important requirements that drive the selection are the types of serial ports or the number of I/O ports available on the microcontroller. The final bus type is a decision that is usually dictated by the microcontroller or the application.

For an SPI EEPROM a 4-pin interface to the microcontroller is necessary. This includes a data input port, a data output port, a clock port and a separate I/O port for the Chip Select of each SPI device. If only 2 I/O ports are available, the SPI or Microwire EEPROMs cannot be selected. Therefore, the bus type that would work best is the I2C or the single I/O UNI/O bus as long as it meets the bus speed and density requirements.

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.

Step 3: Cross Referencing Your Serial EEPROM

How would someone find a Microchip cross reference for a competitor's EEPROM already in use? Microchip has two different tools available for this particular task. This first tool is software based and is called the Memory and Analog Parts Software (MAPS). Learn how you can download this software free of charge at the webpage dedicated to the MAPS Software.

An additional tool that is available for this task is the Serial EEPROM Cross Reference Guide. This powerful tool enables the decoding and encoding of device part numbers from Microchip and several other serial EEPROM manufacturers, simplifying the choice for compatible products. Microchip's cross reference makes the conversion simple, fast and accurate. This PDF file can be downloaded from the following link: Serial EEPROM Cross Reference Guide.

Why do Microchip EEPROMs have such high quality levels?

When cross referencing your EEPROM, you should feel confident that Microchip delivers the highest-quality serial EEPROM products in the world. With world-class line yields, well designed processes, and rigorous Statistical Process Control (SPC) in each of its facilities, a very high quality level is maintained across several hundred million serial EEPROMs shipped each year.

In addition, every Serial EEPROM is tested three times:

  1. At the first wafer-level probe, every die receives 100% AC/DC testing of all data sheet parameters at 90°C or 125°C where all bits are erased and written 5000 times to weed out any failures. (a) Data retention testing includes a 5 to 24 hour Retention Bake at 250°C in-between the first and second wafer probes.
  2. A second wafer-level probe is performed at 25°C, with special tests added to verify data retention, oxide quality and to limit infant mortality.
  3. After packaging, every device receives a final functional test to screen out assembly-related issues.
getting started diagram
Step 4: Selecting Your Serial EEPROM Development Tools
getting Started mplab
total endurance

Are there any specialized Serial EEPROM tools available for the development, design and test phases of a project? Microchip provides some of the best serial EEPROM tools in the industry for programming, testing, evaluating and predicting quality levels of Microchip’s EEPROMs. When basic programming or data viewer is required, the MPLAB® Starter Kit for Serial Memory Products can be purchased without investing a lot of money. Learn how you can purchase one today at the webpage dedicated to the MPLAB Starter Kit for Serial Memory Products. When Erase/Write endurance, device lifetime or quality levels under various voltage and temperature conditions are required, the Total Endurance™ Software can act as a powerful mathematical model to make these predictions. Eventually all serial EEPROMs, from all manufacturers experience bit failures after some number of erase/write cycles. As the only tool of its kind, learn how you can download and operate this software free of charge at the webpage dedicated to the Total Endurance™ Software.