METHOD AND CIRCUIT FOR PROVIDING ADJUSTABLE CONTROL OF SHORT CIRCUIT CURRENT THROUGH A SEMICONDUCTOR DEVICE

摘要

Power Field Effect Transistors are commonly used to provide a series conduction path between a source of operating potential (12) and a load (14). A problem occurs if the load should cause the transistor to become a short circuit during which time rush currents across the FET (10) may seriously damage or even destroy the FET. A solution for limiting short circuit current flow in a Field Effect Transistor (10) and to limit the power dissipated therein includes sensing a rise in the drain-to-source voltage of the transistor and clamping the gate-to-source voltage to a predetermined adjustable value thereby reducing the magnitude of the short circuit current flow to within the safe operating characteristics of the device. A comparator switch circuit (32, 36) is responsive to the drain-to-source voltage of the FET exceeding a reference voltage value for clamping the gate-to-source voltage to a predetermined reduced voltage. A trimmable resistive network (40) is connected between the gate and the source electrode of the transistor for adjusting the gate-to-source clamped voltage potential to compensate for variations in transistor transductances from one transistor to the next that may be used in conjunction with the electronic circuitry.