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M24C04 acknowledges 0x50 to 0x57 instead of just 0x50/0x51

Question asked by Frederic Chasse on Jun 29, 2018
Latest reply on Jul 19, 2018 by Frederic Chasse



I'm using the M24C04 EEPROM with the 5-UFDFPN package.


I can read/write to it without problems, but I just found out that the EEPROM acknowledges not only 0x50 and 0x51, but actually acknowledges 0x50 to 0x57. According to the datasheet, the address of the 5-UFDFPN package should be:

1 0 1 0 0 0 A8


Where A8 is the page number. For the other packages, it's:

1 0 1 0 E2 E1 A8


Where E2 and E1 are pins on the IC. The datasheet says that E1 and E2 are read as 0 in the DFN5 package. But from what I see, it seems that the chip accepts any value of E1 and E2, thus acknowledging 0x50 to 0x57.


I tested that it is indeed this IC that causes the "fake acknowledgements" because the I2C lines of that EEPROM are on a multiplexer, and when the mux disconnects the EEPROM from the uC, I don't get the acknowledgements anymore.


Have you seen this problem before?


Thank you,