| 摘要 |
<p>A LED driver arrangement includes a switching-mode stage (12) to produce a drive current for feeding one or more LEDs (L) from a DC input (10) and a current sensor (18) sensitive to the current fed to the LEDs (L) for producing a feedback signal indicative of the intensity of the drive current fed thereto. The feedback signal is compared with a reference value indicative (20,22) of a LED current as requested by a user, in order to generate a control signal (32) able to drive control circuitry (26,28,30) in order to obtain such LED current. Control circuitry (26,28,30) sensitive to the control signal (32) controls the switching-mode stage (12) so that the drive current fed to the LEDs (L) corresponds to the LED current as requested by the user. An opto-coupler (34) is provided to feed the control signal (32) to the controller circuitry (26,28,30). The opto-coupler (34) is configured to saturate when the drive current fed to the LEDs (L) reaches a minimum level. An auxiliary supply voltage (V aux1 ) for the control circuitry (26,28,30) is derived from an auxiliary winding of a magnetic device of the switching-mode stage (12).</p> |
