Short circuit protection modification

Posted by: mustafaag on 08/08/2014

I've designed a 24V 2.5A flyback PS using TOP266EG with the help of PI Expert software and it did work well. The problem is; when I connect a capacitive load it suddenly draws 5A which causes short circuit reset. The circuit normally draws 500mA or less. I've tested a commercial PS with similar specs with same load and it draws 3.5A top momentarily and don't go into short circuit reset state. What modifications can I do to achieve similar performance? Thanks.

Comments

Hi,

Would you please let me know what is the capacitor value of the capacitive load? The amount of current drawn from the power supply output when connecting this capactive load is dependent on the impedance of the output in the power supply. From different power supplies, the difference of the output impedance causes different current drawn by the capactive load. I would suggest you to try to increase the power supply capacitor value, check if this current is changed or not. You could also add a LC filter with (3.3uH, 100uF) in the output, this filter will help to filter the high frequency ripple, and it may help to decrease this current amount, please have a check.

and total load capacitance is above 4000uF and inbetween 4000 and 5000uF or so I think.

Hi,

Did you check mu suggestions? Do you have any update on the results?

LC filter was already in place. Increasing output capacitor helped very little. I think we should modify control or feedback section.

Hi,

Would you please refer to the loop design from our application note:

http://www.powerint.com/sites/default/files/product-docs/an57.pdf

Thanks