Structure of current measuring circuit

摘要

A current-measuring circuit is provided which is designed to measure the current flowing through an electric load and a switching transistor. The current-measuring circuit includes a current-measuring device. The current-measuring device includes a current-measuring transistor and a voltage control circuit. The current-measuring transistor is disposed in parallel to the switching transistor and allows the current to flow therethrough that is proportional to the current flowing through the electric load and the switching transistor and that is used to measure the current flowing through the switching transistor and the electric load. The voltage control circuit controls a potential difference across the current-measuring transistor so as to match a potential difference across the switching transistor, thereby achieving the proportion of the current flowing through the current-measuring transistor to the current flowing through the switching transistor and the electric load.