I2C on Arduino Due with 5V VDD

Other Hardware 3rd Party Boards
3

Anyway, the safest is always to use logic level shifters.

Very very important statement for the reliable operation of the DUE-MCP4725 setup.

DUE will assert 3.3V as Logic-H on SDA/SCL line. The symbolic name of this signal is VOH. VOH is the maximum voltage that the pin will assume when Logic-H is asserted on the pin.

According to data sheet of MCP4725, the value of VIH is minimum 0.7*VDD = 3.5V at 5V supply at the VDD pin. VIH is the minimum input voltage that will be recognized as logic-H state.

So, the MC4725 will very likely fail to recognize the SDA/SCL signals (3.3V) as Logic-H because it is below the specification of VIH which is 3.5V.

Therefore, use a voltage level sifter or operate MCP4725 at lower supply voltage (range: 2.7V to 5.5V).