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What is Semiconductor Memory?

EEPROM I/F Features

■Interface Selection

Generally, serial EEPROMs utilize 3 types of interfaces - Microwire, SPI, and I2C - each providing distinct advantages.
Users should select the ideal interface based on application requirements.


There is a limit to the number of MCU ports that can be used. When seeking to minimize the number of ports used for EEPROM I/F, I2C, which requires only 2 lines for MCU control, is recommended.
In addition, multiple EEPROMs can be connected on the same bus without adding ports, making I2C ideal when utilizing more than one EEPROM in the same set.
One drawback, however, is the relatively slow communication rate (400K to 1Mb/s). This limits the access time, rendering it unsuitable for high-speed applications.


  • Enables communication using only 2 wires, reducing the number of MCU ports required
  • Multiple EEPROMs can be connected to the same bus



For high-speed communication, SPI, which is capable of speeds up to 20Mb/s, is the preferred choice.
Also, because higher speeds are possible, EEPROMs with capacities as much as 1Mbit are offered.
However, SPI requires 4 wires for communication -double the amount of I2C.


  • High operating frequency enables high communication rate
  • Broad capacity range



This older communication method is slower than SPI and is only available in smaller capacities. Also, like SPI, 4 wires are needed - twice as much as I2C.


  • Slower communication speeds than SPI
  • Available only in smaller (memory) capacities


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