I am using LM317 to get 5.5V out of 12V input
In my circuit R1 is 220R, R2 is 741R Expected current is ~700mA. link to the data sheet
This of course will produce a lot of heat, so I choose quite a large heat sink. when working, The heat sink is getting very hot, I will probably have to replace it.
The strange thing however is that after about 2 minutes the output voltage rise to 8 to 9 volts.
This is very strange as I expected the overheat protection to protect this from happening.
Removing the heat sink altogether is followed by a drop of the regulated voltage as expected.
So, I am suspecting that the heat sink keeps the LM317 working, but something else is causing the voltage to drift upwards.
I will appreciate any explanation for this phenomena.