Other Parts Discussed in Thread: DAC121C081, , DAC43608
I was guided to this forum by Jejomar Ildefonso from TI customer support. Here I found the following thread that might be related in some kind to our issue:
DAC121C081: I2C Addressing Question by Adam Daluga
Though we are not operating our two DACs on different potentials, we also see address select pins that are read high instead of floating. Also the above thread was taken offline so I could not see a conclusion on this. Here's how our story goes:
We are using two DAC5578 in one of our designs along with several other I2C bus slaves. The assigned addresses are 0x4E and 0x4F. A certain number of DAC's latches a wrong I2C address only in a limited range of board temperatures. For all failing DAC's the temperature range where the issue occurs is between about 18°C and 26°C. Outside this range (tested temperatures from -20°C to +85°C) the address is set correct. The issue seems to be related to the individual physical IC, since swapping a failing and a good DAC also swaps the occurrence of the issue to the other address on the bus. All observed occurrences turn 0x4E to address 0x49 and 0x4F to 0x4B. So the floating address input pin seems to be interpreted as high instead of floating!
What can cause this behavior?
Many thanks for your support,