Patent ID: 8634213

Claim:
A power converter for delivering an output signal to a load, the power converter comprising: an energy transfer element having an input side and an output side, the input side for coupling to an ac line voltage and the output side for coupling to the load; a power switch coupled to a primary winding of the energy transfer element for regulating a transfer energy of the output signal delivered to the load; a controller that generates a pulsed drive signal having a frequency in response to a control signal, the pulsed drive signal being coupled to control switching of the power switch such that the frequency determines the transfer energy; a feedback circuit coupled to receive the output signal and a command signal, in response thereto the feedback circuit generating the control signal coupled to the controller; wherein when the control signal is within a first range the controller operates in a closed loop feedback mode such that the output signal is regulated at a certain value, when the control signal is in a second range, the controller operates in a limiting mode in which the controller limits the output signal to a maximum value, when the control signal is in a third range, the controller operates in an open loop mode in which the command signal implements a pulse width modulation (PWM) dimming operation with respect to the output signal delivered to the load, and when the control signal is in a fourth range, the controller a operates in a protection mode in which the controller turns the power switch off and does not restart switching.