There are two limitations on the power handling ability of a transistor: average junction temperature and second breakdown. Safe operating area curves indicate IC VCE limits of the transistor that must be observed for reliable operation; i.e., the transistor must not be subjected to greater dissipation than the curves indicate. The data of Figure 1 is based on T J(pk) = 150_C. TC is variable depending on conditions. Second breakdown pulse limits are valid for duty cycles to 10% provided T J(pk) 150_C.