Monitoring of low currents through a low-side driver DMOS by modulating its internal resistance

摘要

Relatively low currents are monitored through an integrated DMOS power transistor in a low-side driver configuration. A feedback circuit is responsive to the voltage applied to a gate of the DMOS power transistor to limit the minimum value to which the drain-source voltage may drop to keep it sufficiently high, and to allow a reliable monitoring of the current through the power transistor, even at relatively low levels. This is performed by increasing the conduction resistance of the power transistor at low current levels.