Hi. the LM338T (TO-220) is rated for up to 5A. I had configured the regulator circuit to +5V output (with +9V input) and attached a 2 ohm 50W resistor load to test.
At 2.5A it got very hot then thermal shutdown occurred after about 30 seconds. I then added a 12.5TR (thick) heat sink. It now lasted up to 35 seconds before it got really hot. Shouldn't the LM338T stay "relatively" warm at half its rated current? what can I do to keep it cooler? thanks.