| 摘要 |
<p>An LED driving power supply comprises a comparator (U6), an optocoupler portion, a transformer (T1) having a primary main winding (T1-A), a secondary main winding (T1-D), a primary auxiliary winding (T1-B), and a secondary auxiliary winding (T1-C), and a control chip (U1) connected with the primary main winding (T1-A) and the primary auxiliary winding (T1-B). The secondary main winding (T1-D) is connected with a current detection end (-IS) of an LED load through a detection resistance (R13), which converts a current variation of the LED load detected by the current detection end (-IS) into a voltage variation. The voltage variation is compared with a reference voltage through the comparator (U6), the output of which is fed back to a feedback loop function control pin of the control chip (U1) through the optocoupler portion. The voltage of the feedback loop function control pin is compared with a voltage of an inner crystal oscillator of the control chip (U1), thus the duty cycle width of the grid voltage of an inner field-effect transistor of the control chip (U1) is adjusted to perform an average current control.</p> |
