Dear Sir/Madam,
I made flyback converter according to the tida 01622 application note with UCC28780 ACF controller. When i supply the converter with AC supply, then controller does not have a supply voltage. Because according to the picture controller's supply pin VDD has connection only transformer auxiliary pin and at the starting point transformer has no energy because of QL switch is off position. If controller does not take power then there is no PWM signal and QL switch is still off position. For supplying controller i remove between VDD pin and auxiliary transformer 2 diodes . Then i used DC source with 18 V. I supplied first cpnverter with AC source and then controller with DC source. After the supplying controller, Dhvg1 TVS is exploded. Why TVS is exploded do you think? How can i energize the controller? I am confusing whit this schematic. I wait for your response as soon as possible.
Thanks
