Hello I have a LM7812CT power regulator and I want to use it to convert a 28V dc to a 12V dc.

I am using the circuit provided in the data-sheet using 2 capacitors, one 0.33uF connected to the input voltage pin(1)and the ground ,and one 0.1uF connceted to the ground and the output pin(3).

My problem is that I get output voltage 3.9-4.0 Volts.

http://freedatasheets.com/datasheet-download/d82cf2f20ef6f7701ba6a5e5e697dd3d/LM7812 link for datasheet

I get this value even with 12V supply to input.

How can i fix it to get my 12V?

Where do you think am I wrong? Is it burned??

Any ideas welcome

edit:: ok guys the LM7812ct was burned after all. I replaced it and everything worked ok!! thnx and keep up the good work