This paper introduces the design of High-Voltage CMOS drivers for Electrostatic MEMS switches. In order to perform online diagnosis, the proposed architecture implements a dedicated circuitry that can detect the pull-in event. This way, stuck or broken switches are identified during operation. The pull-in event corresponds to a rapid change in the actuation capacitance thus producing a current peak during actuation. The idea is therefore to measure the charging current, using a differential method that cancels the effects of any parallel parasitic capacitance.