The electrothermal model of the linear power supplies

This paper deals with the problem of modeling of the linear 3-terminal positive-voltage regulator MA7805 (IC) with selfheating taken into account. In the construction of the electrothermal macromodel (ETM) the modified electrical SPICE-library model of the considered device has been used. This macromodel has been implemented to SPICE with the use of the ABM option. The analysis is performed alternately with the use of SPICE for the electrical power calculations at the fixed temperature and the JUMPS special tool designed to calculate the junction (inner) temperature at the fixed power value. For each point on the nonisothermal device characteristic after some iteration, the steady-state is achieved. The proposed macromodel was verified experimentally and a good agreement between the calculation and measurement results was obtained.