In most of my previous projects which are needed to a temperature sensor
I was using smt160 (smart digital temperature sensor).
It is a duty cycle modulated square wave output voltage with linear response
to temperatures in the -45°C to +130°C range
Outout and temperature relation:
DC = 0.320+0.00470*T DC = Duty Cycle
T = Temperature in °C
I measure DC for 1000 times and then i put duty cycle average in to equation


3 weeks ago i was working on a project which most of ic's were IIC interfacing
so this time i preferred using LM75 (another digital temperature sensor with
IIC interfacing) instead of smt160
I used it,there was not any problem there.
But today accidently i find that measured temperature
using lm75 and smt160 have a difference equal 2-2.5 °C
It made so wondering me!!
I refer to both of datasheets
Temperature Accuracy of smt160 is:

-30°C to +100°C ± 0.7°C(max)
-45°C to +130°C ± 1.2°C(max)

Temperature Accuracy of lm75 is:
−25°C to +100°C ±2°C(max)
−55°C to +125°C ±3°C(max)

Now it is my question:
What is accurate current temperature !
Thanks From all who give me their idea.
Mehdi