The DS28EC20 from Maxim is a 1-Wire EEPROM memory building block, housed in a cheap TO-92 package and a size of 20480 bits. The memory is divided into 80 pages of 256 bits each; an additional page is reserved for control functions. Data is initially written to a scratch pad of 32 bytes, then verified and finally copied to the EEPROM memory. An unusual feature of this component is that blocks of 8 pages can be protected against writing or can be configured into an EEPROM mode, where bits can only be programmed from a ‘0’ into a ‘1’.
Communications with the DS28EC20 is achieved via a single wire bus conforming to the standard 1-Wire protocol. Every IC has a unique 64-bit registration number that is used to address specific ICs in a multi-drop 1-Wire environment. The IC is largely backwards compatible with well-known memory building blocks such as the DS2433.
The life-expectancy of the chip is specified at more that 200 k erase/write cycles at 25 °C. The I/O pin has IEC 1000-4-2 Level 4 ESD protections (8 kV contact, 15 kV air).