Hi, I am evaluating DER 136 design for driving 36 High power LEDs 6 in series & parallel combination. I have developed it as per the standard design. There are a few issues for which i want support to complete the design. Below are the problems. 1. Output voltage = 28Volts No load as against 24V standard. 2. output voltage = 19Volts with load (LED string Voltage). 3. output current 2.8A (oscillating from3.5A to 2.4A). 4. LEDS are flickering. 5. voltage is constant & regulation is also good. 6. PF is 0.9 7 Efficiency is poor 78% as against 85% standard design claims. Can any body help me to resolve this issue. Regds, vinay