Patent ID: 6727679
Filing Date: 2004-04-27
Classification: H02J,H02M

Abstract:
A DC to DC voltage converter circuit for use with power tools having a motor operable with DC voltage power and at least one battery having positive and ground terminals for supplying power to the converter circuit at a predetermined voltage, the converter circuit providing power at one or more desired operating voltages and comprising:a ground line connecting the battery ground terminal to the motor; a capacitor connected in parallel with the motor; a switching transistor having a first terminal connected to the battery positive terminal and a second terminal connected to one end of an inductor that has its other end connected to ground, and a switching control third terminal that can switch the transistor into and out of conduction responsive to switching signals being applied thereto; a controller for generating and applying said switching signals to said third terminal, said switching signals having an adjustable frequency and an adjustable duty cycle of conduction and non-conduction within a predetermined range; wherein said controller can provide switching signals that cause said converter circuit to supply power at desired operating voltages that are selectively above and below said predetermined voltage.