0167.LM2678T_ADJ_Circuit_Diagram.pdf
Hi, Attached is schematic of LM2678 IC . The circuit works well. Good line and load regulation in full O/P voltage range (2V-24V),
withstand dead-short load condition, output recover smoothly after removal of dead- short, no
heating of component. But IC LM2678T burns at site after 1-2 months of normal work.
After analysis, found 40- 54V spikes at Pin-1(VSW) of IC.
Now added one electrolytic cap- 10uF/63V at I/P pin-2 to gnd (close to IC) and RC snubber
network (10E- 10nF) across Pin-1 to GND. Spikes are slightly reduced but still cross the
maximum voltage rating of 40V.(around 45-48V).
Is it the reason for failure?
Please suggest solution to resolve the problem.
Regards
Atul Bhakay
