M24512-A125 Datasheet, PDF (24/40 Pages) STMicroelectronics – Automotive 512-Kbit serial IC bus EEPROM with 1 MHz clock

Application design recommendations
M24512-A125
5.2
Cycling with Error Correction Code (ECC)
The Error Correction Code (ECC) is an internal logic function which is transparent for the
I²C communication protocol.
The ECC logic is implemented on each group of four EEPROM bytes^(b). Inside a group, if a
single bit out of the four bytes happens to be erroneous during a Read operation, the ECC
detects this bit and replaces it with the correct value. The read reliability is therefore much
improved.
Even if the ECC function is performed on groups of four bytes, a single byte can be
written/cycled independently. In this case, the ECC function also writes/cycles the three
other bytes located in the same group^(b). As a consequence, the maximum cycling budget is
defined at group level and the cycling can be distributed over the 4 bytes of the group: the
sum of the cycles seen by byte0, byte1, byte2 and byte3 of the same group must remain
below the maximum value defined in Table 6.
Example 1: maximum cycling limit reached with 1 million cycles per byte
Each byte of a group can be equally cycled 1 million times (at 25 °C) so that the group
cycling budget is 4 million cycles.
Example 2: maximum cycling limit reached with unequal byte cycling
Inside a group, byte0 can be cycled 2 million times, byte1 can be cycled 1 million times,
byte2 and byte3 can be cycled 500,000 times, so that the group cycling budget is 4 million
cycles.
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b. A group of four bytes is located at addresses [4*N, 4*N+1, 4*N+2, 4*N+3], where N is an integer.
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