Low dim turn on

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I built a driver usingRDR-251. It dims fine, but will not turn on at low dimming when the power is cycled. Would the DER-296 circcuit using the LinkSwitch-PH do better?


For low power applications, the primary reason why the LED driver is unable to power up at low dimming angle is due to insufficient holding and latching current of some triac dimmers. This was explained in the RD-251 and DER-296 report. If the triac is unable to turn ON, then you can't turn ON the LED. One solution is to use heavier R-C bleeder and damper to draw higher current in hope of turning ON the triac. Again, the performance may vary depending on the dimmer you use.


DER-296 has certain features different from RD-251. However, with respect to low phase angle dimming, there may not be a huge difference in performance between the two. It still boils down to whether the triac can turn ON or not at a specified phase angle.