In a single-chip microcomputer including a nonvolatile semiconductor memory device and write, read and erase circuits for performing a write operation, a read operation and an erase operation upon the nonvolatile semiconductor memory device, respectively, a sequencer is connected between the write, read and erase circuits and an interface. The method executes a function by a processor; provides the electronic overload protection by the function executed by the processor; and adjusts the thermal trip level by the function executed by the processor in order to mimic adjusting a physical thermal characteristic of a thermal time constant of a fixed mechanical system. Lattice quality of GaN-based epitaxy on the sapphire substrate is improved, and the internal quantum efficiency of GaN-based LED epitaxy is increased.