Flickering LED driver Posted by: bonakdar on Wed, 02/01/2012 Hi Engineer I have designed a LED driver with LNK413EG, output 3.25V 2A. I have designed it with Power Integrations Excel software. But now, when testing, the output is flickering. Can you guide me? 回應 Could you send us your spreadsheet, schematic, and layout? Dear Engineer Please check the attached file. The PCB layout for transformer is not fitted to RM10. So we used wires to connect the PCB to the RM10 transformer. Best regards Mohammad Reza Bonakdar I am sorry but I can not open your attached files. Please send us your schematic and layout in . pdf format. RM10 is oversized core for 6.5W output. RM8 is more than enough for the power level as shown in the attached file. Dear Engineer My design output is 2A. So when I select RM8, PI software give many alarms and warnings. Just accept RM10. If my design is not correct, can you design a correct 3.25V, 2A LED driver using LNK413EG? Best regards Mohammad Reza Bonakdar Did you send us your schematic and Layout in .pdf files? I attached spreadsheet with RM8 in my previous response, and I attached another spreadsheet with RM10. Dear Engineer Please check the 3 attached files. These are the correct files. I have not used RM8. I just used RM10. Best regards Mohammad Reza Bonakdar 1) The schematic shows LL4148 diodes in the bias and OVP sense circuit, D5 & D6, and PIXL spreadsheet shows the PIV of the bias voltage is 125 V. You need to change these diodes to higher PIV diodes. 2) If flickering did not go away with new diodes, you might want to remove Q1 in the circuit and to see whether flickering is caused by OVP circuit. If it does, you need to change VR2 to higher voltage. Dear Engineer I changed the diodes and tried my LED driver again. But result is exactly same as before. I changed the two connections of transformer secondary with each other, just the driver output (+) and (-) changed. Now, I have a question. Is it possible to order the LED driver designs to Power Integrations. Means for example order a LED driver design with 3.25V DC, 2A output to Power Integration, and pay Power Integrations for the design. Is it possible? Best regards Mohammad Reza Bonakdar Dear Engineers My company is specialized in LED lighting products. We have automatic SMT machines. So we produce our LED drivers ourselves. We have some good choices for the LED drivers ICs like Fairchild, Iwatt and Power Integrations. PI ICs are the most expensive LED driver ICs with x2 prices. But we believe and trust to PI ICs more than other choices. Our LEDs life time is more than 150,000 hours. So to can make the long life and efficient LED drivers we want to use PI ICs. As the first step, we want to use LNK413EG to make an LED driver with following specifications: 1) Input: 90-265V AV universal 2) Output: 3.25V, 2A DC 3) Using one-layer PCB 4) prefer to use surface mount Diodes, resistors and capacitors 5) USE electrolytic capacitors (5000h to 10000 hours life time) 6) Efficiency > %80 7) PF > 90 8) Using RM6 or RM8 for transformer We need the best design (Schematic and PCB layout) or this driver from you. Our company engineers could not reach to desired results with your ICs because of their low experience in your ICs. We accept pay you for the designs. Can you do it for us? Then we can use your company ICs much more. Looking forward to hearing from you soon. Mohammad Reza Bonakdar You can buy RD195, which is universal input, dimming, 28V_0.5A reference board using LNK406. Also you can get engineering support from our local PI sales office, where several field application engineers are supporting our customer's designs using PI products.