Current measurement via gate of external transistor

摘要

A control circuit for a switch, configured to measure the drain-to-source current of the switch is described. The control circuit is configured to control an external transistor and comprises a control pin coupled to the gate of an external transistor. The external transistor and a level shifting unit are coupled to the control pin and configured to isolate an AC current from the control pin; at a time instant subsequent to the first pulse duration, the isolated AC component of the voltage potential is indicative of a drain-to-source current through the external transistor.

主权项

1. A control circuit configured to control an external transistor to switch from an off-state to an on-state, wherein the external transistor comprises a gate and a source, wherein the source of the external transistor is coupled to a shunt resistor, the control circuit comprising:
a control pin configured to be coupled to the gate of the external transistor; a high side control switch coupled to the control pin and configured to generate a pulsed on-signal by coupling the control pin to a supply voltage of the control circuit for a first pulse duration, thereby putting the external transistor to the on-state, when the external transistor is coupled to the control pin; and a level shifting unit coupled at a first end to the control pin and configured to isolate an alternating current, referred to as the AC, component of a voltage potential at the control pin; wherein at a time instant subsequent to the first pulse duration, the isolated AC component of the voltage potential is indicative of a drain-to-source current through the external transistor, when the external transistor is coupled to the control pin.