Detail of driver :
- Topology: DER-344 example : 12.8W Tapped Buck Led Driver
- Input: 185-265 VAC
- Output: 20W – 20Volt 1Amp
- Usage: Outdoor Streetlight
- Testing: 24Hour with high temp, Lower & higher volatage applied, 1 lac time on/off tested
- Protection: No open voltage protection applied as it not needed
Driver condition after failure:
- L2-S of LNK419 - D of LNK419 - D3 - pin#5 of T1 track was fully burn.
- D2 Diode also burnt up with track
- Led was also burnt
- LNK419 IC burnt
- Failure Ratio: 5 failed out of 15 drivers after 2 month of usage
Changes made on DER-344 (Circuit diagram file attached) – To meet my reauirements
- Added 8mH filter chowk as emi filter after fuse.
- R3 + R11 : 4M to change maximum voltage shutdown
- R5 : 1.5M to change minimum voltage shutdown
- C8 : 33nF 100V for better regulation
- D2 : ES6D (ES3D x 2 parallel)
- C5 output cap: 2000uF 25V (2 x 1000uF 25V) for better THD
- C3 : 4.7uF 400V for better surge protection
- U1 IC : LNK419 to make 20W driver
- C4 bias Cap: 10uF to run on reduced power mode
- VR1, VR3 : removed not needed open circuit protection
- Driver was potted with PU epoxy.
I have made 20W and 30W non dimming driver with potting and it running since 1 year. I have never seen problem like that before.
Please let me know the reason of IC failure. Because I have sold many items with this driver recently.