This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
Hi Kensuke,
Let me look into this and get back to you.
-Michael Wong
Hi Kensuke-san,
Yes it is possible to read abnormal temperature data when there is power supply noise. The noise may be turning off the part when it falls below 2.7V.
Make sure there are enough bypass capacitors to remove the power supply noise.
-Michael Wong
Hi Kensuke-san,
The architecture of the internal power-on-reset works best with a ramp of 0.7V/msec or faster. To avoid potential abnormal temperature reading due to slow ramp we recommend the power up sequence described in page 19 of the datasheet.
-Michael Wong
Hi Kensuke-san,
There is no specific value for the abnormal data. It is random and varies depending on the part and ramp rate.
To answer your second question, a bypass capacitor is needed at the VDD pin of the device to reduce the power supply noise. The scope picture attached to the original question shows a 1.34V peak to peak noise, add a capacitor that reduces this noise to 100mV. I cannot provide an exact capacitor value as it entirely depends on the system.
-Michael Wong
I had the same problem! Russell Bodine
________________________________________________