Patent ID: 8330401

Claim:
A circuit unit for driving an electronically commutated fan motor controllable using a pulsed operating voltage, the circuit unit comprising: two terminals for carrying the pulsed operating voltage; a power stage comprising at least one transistor having a switching path for driving at least one winding of the fan motor, the switching path of the at least one transistor being arranged in series with the at least one winding of the fan motor, wherein the pulsed operating voltage is applied to a terminal of either the at least one transistor or the at least one winding of the fan motor without performing smoothing of the pulsed operating voltage; a control stage for driving the power stage; a first diode through which the pulsed operating voltage provided by the two terminals and used by the control stage is separated from an operating voltage of the power stage; and smoothing circuitry coupled to the first diode and the control stage for smoothing the operating voltage of the control stage.