Hello,

We are currently seeing an offset while trying to read remote temperature. There are actually two sensors in the remote device, one for internal and one for external measurements. Now:

-When default ideality factor is not used, these two vary about 1deg C. However, if n=1.03 (value suggested by FPGA manufacturer) is programmed into the device the difference is about 8deg C. (0xD4 is written into the 0x23 register)

-The remote value readout is stable, no significant jumps, so probably no noise issues

-I found out that TMP451 device actually uses 3 different currents to readout, which might be out of the part spec? (unfortunately I did not came across that would satisfy all the requirements and all the parameters were in the recommended region)

-There seem to be no noise on the supply input and is decoupled with 100nF (Vdd=1.8V)

-The part input filter is currently 2x47R + 100pF. Trace length between the temperature sense diode and TMP411 input is about 9mm, no obvious noise source signals nearby

-Remote sensor specifications:

Many thanks for any suggestions.