AnsweredAssumed Answered

Weird ADC temperature sensor results

Question asked by gt on Jul 31, 2013
Latest reply on Aug 1, 2013 by baird.hal.001
I am trying to use internal temperature sensor of STM32VLDiscovery board but I have a little problem. I get ADC conversion result and apply the formula in RM0008, 
temp = (V25-Vsense)/Avg_slope+25, to calculate temperature. I use typical values V25 =(1.41/3.3)*4096=1750 and Avg_slope = (0.0043/3.3)*4096 = 5. However, I obtain a negative temperature value around -4oC.  

I am not sure if the following is logical or not but after getting negative values, I looked Vref_adc and saw it is 1643, so I changed V25 to 1.41*1643 = 2317 and Avg_slope to 0.0043*1643 = 7.06. This time, I obtain positive values but around 80oC. Is this normal?
Thanks in advance.