Patent ID: 8653759
Filing Date: 2014-02-18
Classification: H05B

Abstract:
1. A ballast or driver for powering at least one light source, comprising: a ballast or driver input with first and second ballast or driver input terminals for receiving AC input power; a rectifier circuit operatively coupled with the ballast or driver input to convert the AC input power to provide rectifier DC output power at first and second rectifier output terminals; an output power stage comprising at least one power conversion circuit operatively coupled with the rectifier output terminals to convert the rectifier DC output power to provide ballast or driver output power to the at least one light source; a DC bus capacitance coupled between the rectifier and the output power stage; and a shunt circuit comprising first and second shunt circuit nodes coupled between the ballast or driver input and the DC bus capacitance, the shunt circuit being operative to provide a high impedance greater than or equal to an impedance threshold between the shunt circuit nodes when the AC input power is greater than or equal to a power threshold value, and to provide a low impedance below the impedance threshold between the shunt circuit nodes when the AC input power is below the power threshold value.