A Method of Measuring the Transient Thermal Impedance of Monolithic Bipolar Switched Regulators

Abstract

In the paper, a new electrical method of measuring the transient thermal impedance <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Z</i> ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> ) of monolithic switched regulators with a bipolar junction transistor as a switch, is proposed. In the method, based on the cooling curve, the electrical power is dissipated in the considered device operating in the boost converter being their typical (catalogue) application circuit. As a thermally sensitive parameter, the voltage across the body diode is used. The general conception of the method is presented. As an example of the realization of the method, the measuring set for LT1073 operating in the boost converter is described and examined in detail. The correctness of the method was proved by means of the known (standard) electrical method and the infrared method, in the wide range of changes of the power dissipated in the investigated device as well as at various conditions of the device cooling.