| 摘要 |
A driver device provides variable electric current to at least one semiconductor light-emitting device. It comprises a switched-mode power supply with a current switch for generating an output current of the driver device, and a switch driver circuit (202) to provide switching pulses to said current switch (201) at a switching frequency. The switch driver circuit (202) responds to voltages exceeding a first threshold at a control input (EN/DIM) by enabling the providing of switching pulses. It responds to voltages between said first threshold and a second, further threshold by allowing an amplitude of a measured current to reach a value proportional to the voltage at the control input. A control pulse formatter (203) provides the control input (EN/DIM) with control pulses of variable amplitude exceeding said first threshold at a pulse width modulation frequency smaller than said switching frequency. |
