Hi Christian,
The equation 2 mentioned in the Application Note EE-346 on Page 5 is wrong.
The equation 3 used is correct.
You can see the correct formula on page 14 of the ADM1032 datasheet . The link for the datasheet is given below:
http://www.onsemi.com/pub_link/Collateral/ADM1032-D.PDF
Thanks,
Harshit