Patent ID: 8933635
Filing Date: 2015-01-13
Classification: H02M,H05B

Abstract:
1. A method to prevent ringing in Discontinuous Conduction Mode (DCM) of a boost converter for a white LED driver, comprising the following steps: (1) providing a high-voltage WLED asynchronous boost converter, driving one or more WLEDs connected in series, wherein the boost converter comprises a port for an input voltage, an inductor, a diode, a power switch, wherein the inductor, the diode, and the power switch are all connected to a LX node; (2) sensing a fast falling edge of the voltage at the LX node in order to immediately initiate shorting the inductor if required; (3) shorting the inductor when the current through the inductor reaches zero during DCM mode by a coil switch across the inductor, wherein the coil switch comprises two identical HV enhancement NMOS devices sharing a bulk, which is connected to an NMOS transistor N (4) turning on the coil switch, if required, by lifting the gate of the coil switch above the input voltage level.