Control system and method for adjusting dimming range of lamp

A control system for a lighting device, comprising:

• a driving circuit configured to be electrically connected to the lighting device and to output a driving signal for driving the lighting device to emit light, and including a driving switch that is configured to adjust a conduction angle of the driving signal;
• a current detection circuit configured to be electrically connected to the lighting device, to detect a current of the lighting device, and to output a detection signal indicating the current of the lighting device based on the current thus detected;
• and
• a control unit electrically connected to said driving circuit and said current detection circuit, and configured to
• receive the detection signal from said current detection circuit,
• control said driving switch to switch between a conducting state where the driving signal is in an on state, and a non-conducting state where the driving signal is in an off state, such that the driving signal is in the off state for a pausing time period from a zero-crossing of a sine waveform corresponding to the driving signal, and changes to the on state for an active time period immediately after the pausing time period until a next zero-crossing of the sine waveform, and
• implement a calibrating process to control said driving switch to gradually extend the pausing time period across successive wave periods of the driving signal, so as to gradually reduce an average voltage across the successive wave periods of the driving signal for reducing brightness of the light emitted by the lighting device, in response to determining that the current of the lighting device indicated by the detection signal corresponds to an unstable condition where the lighting device is one of flickering and turned off, to obtain critical dimming information related to the driving signal that is outputted when the unstable condition of the lighting device occurs, and then to obtain a limiting threshold for adjusting the brightness of the lighting device based on the critical dimming information.