Hello
I am having an issue with a UCD90120A device, specifically related to the internal temperature sensor.
According to the UCD90120A datasheet, the accuracy of the internal temperature sensor is +5/-5 degrees C.
Using TI Fusion Design, I have a device that is reporting an internal temperature that is between 8 and 10 degrees C too cold for the actual ambient temperature. The ambient temperature is stable and the temperature of the board onto which the device is populated is also stable.
The internal temperature measurement does track ambient conditions. So if I spray the device with cold spray I see the temperature drop and then rise slowly back up to the ambient temperature.
So the only real problem is the 8 to 10 degrees C offset. Is there any way to calibrate the internal temperature sensor? Is the internal temperature sensor calibrated as part of device programming? Is there any way that the internal temperature sensor could have lost it's calibration?
We have manufactured about 10 boards so far with these devices and up until now the internal temperature measurements have been OK. This is the first device to exhibit this behaviour. I have confirmed that all the power supply connections to the device are good. I have also confirmed that the device is measuring the rail voltages correctly (so this rules out the internal ADC reference and ADC). It is only the internal temperature measurement that is wrong.
I am not sure what could be causing the internal temperature measurement to be out by so much. Any advice or feedback would be appreciated!
Thanks
Gavin
