M24C04-F DNF5 & UFDFPN8 I2C addresses

[MMici.1]

Dear All,

I would like to confirm that two M24C04-F, one in a DNF5 package and one in a FDFPN8 cannot be used together on the same bus. Is that correct?

To provide some background, we are using M24C04-F DNF5 but there is a need to add another EEPROM on the same bus. Adding UFDFPN8 device with accessible E1,E2 pins should allow us to add another EEPROM with a different address, however, we found out that the DNF5 variant actually responds to multiple I2C addresses, not just 0x50/0x51 as defined in the DS.

The DS states that the pins E1, E2 aren't accessible but E1, E2 bits must always be set to logic 0 for proper communication with the DNF5 variant. However, it also states that "No other I2C device using address 1010 xxxx (x = don't care) can be connected to the same bus."

I assumed that the E1,E2 are set to 0 internally in the DNF5 variant but it seems more like they aren't checked during addressing. Can someone from ST provide the reason for this? 

Thank you for the information.

[Pierre P. · Accepted solution]

Hello,

I can confirm the statement that "No other I2C device using address 1010 xxxx (x = don't care) can be connected to the same bus.".

Indeed, the M24C04-F DNF5 responds to multiple address 0x50 up to 0x57.

Best Regards

Pierre

[MMici.1]

Hi Pierre,

thank you for the confirmation.

Can you provide the reason for this, i.e. responding to multiple addresses rather that just 0x50/0x51? 

(I'm not trying to nit-pick, I'm genuinely interested.)

Kind regards,

Matt