Schaltungsanordnung zum Erfassen des Laststroms eines Leistungs-Halbleiterbauelementes mit sourceseitiger Last

摘要

The circuit has an additional FET to sense the load current of a power FET. The power FET has a drain connected to a power supply, and a source connected to a load. The drain and the gate terminals of the two FETs are connected in parallel. A current corresponding to a division of the load current flows through the additional FET. A controllable resistor is connected between the source of the current sensing FET, pref. a MOSFET device, and ground. The resistance value is set so that the drain-source voltages of the power FET and the sense FET are equal. Therefore the measurement current is proportional to the load current independent of the size of the load. The measurement resistor may be made of poly-silicon, or it can be a temperature-compensated resistor.