LED DRIVING METHOD AND CIRCUIT USING LINEAR AND SWITCHED MODE DESIGN

摘要

A method and driver circuit for driving a LED lamp from a dimmer supplying a mains supply dimmer voltage between a minimum cut mains supply voltage and an uncut mains supply voltage. In the method and driver circuit, a DC supply voltage is generated from the mains supply dimmer voltage, and the DC supply voltage is supplied to the LED lamp. A current source is coupled in series with the LED lamp. An amount of cutting of the mains supply dimmer voltage is used to generate a pulse width modulation, PWM, signal having a duty cycle range between 0% and 100%. The current source is driven with the PWM signal to generate a predetermined pulse width modulated current through the LED lamp. The DC supply voltage is controlled to keep a voltage across the current source at a predetermined value.