m24c64-df STMicroelectronics, m24c64-df Datasheet - Page 18

• Manufacturer Part Number: m24c64-df
• Description: 64 Kbit Serial I?c Bus Eeprom
• Manufacturer: STMicroelectronics

Device operation
4.10
4.11
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Lock Identification Page (M24C64-D only)
The Lock Identification Page instruction (Lock ID) permanently locks the Identification Page
in Read-only mode. The Lock ID instruction is similar to Byte Write (into memory array) with
the following specific conditions:
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If the Identification Page is locked, the data bytes transferred during the Lock Identification
Page instruction are not acknowledged (NoAck).
ECC (Error Correction Code) and Write cycling
The M24C64 devices identified with the process letter A or K offer an ECC (Error Correction
Code) logic which compares each 4-byte word with its associated 6 EEPROM bits of ECC.
As a result, if a single bit out of 4 bytes of data happens to be erroneous during a Read
operation, the ECC detects it and replaces it by the correct value. The read reliability is
therefore much improved by the use of this feature.
Note however that even if a single byte has to be written, 4 bytes are internally modified
(plus the ECC bits), that is, the addressed byte is cycled together with the three other bytes
making up the word. It is therefore recommended to write by word (4 bytes) at address 4*N
(where N is an integer) in order to benefit from the larger amount of Write cycles.
The M24C64 devices are qualified as 1 million (1,000,000) Write cycles, using a cycling
routine that writes to the device by multiples of 4-byte words.
Device type identifier = 1011b
Address bit A10 must be ‘1’; all other address bits are don't care
The data byte must be equal to the binary value xxxx xx1x, where x is don't care
Doc ID 16891 Rev 23
M24C64-DF, M24C64-W, M24C64-R, M24C64-F