Hi Atul,
You can also look at TMP451. It has the fastest conversion time and the highest accuracy.
If the temp sensing transistor is a standard descrete part (e.g. 2N3906 or 2N3904), the n-factor is the only thing that can vary between manufacturers and affect significantly teh accuracy. In all our remote temp sensors, there is a register for programming a different value than the default 1.008. The specific value could be found in the datasheet spec or requested by the transistor manufacturer.
The other variations such as reverse saturation current and series resistance are cancelled internally by the temperature calulation algorithm. This is done by taking the difference between Vbe at several precision currents forced through the remote transistor, which practically cancels the non-temperature dependent variations.
Regards,
Vasco