DPA switch start-up problem.
I'm using DPA switch for DC as well as AC input SMPS.
Though it is only recommended for DC- DC converter. problem is that, for AC input power supply does not start at desirde limit.
For DC it starts with 16.4 VDC but for AC it takes 26.7V.
I have increase the value of capatitor but inrush current is very high with larger value of C.
What should i do now??
Should i change my design??
pl let me knw what can be done to avoide such kind of problem.
Comments
If i use inrush limitting resistor then again starting up voltage going to increase.
And one more problem i am facing is that for DC wen supply starts up intially it takes too high current i.e. 500 mA instead of 120 mA for 1 V.
Means supply starts at 14.9 VDC and from this point upto 16.1 V it takes 500-600 mA current.
After that it will get stable and if i again reduce voltage from higher to lower than this type of problem does not occure.
if i use UV (under voltage) lock out circuit then it affects AC startup.
I have tried with many values of capacitor and inductor in PIE type filter.
But i am not getting result.
Whats the problem in this case?
My transformer is faulty or what?
If voltage is too low with inrush resistor then you proabably are using device beyond it's practical range
If design starts at 16VDC then there must be too little bulk cap if it can't start at 26.7 V. I am assuming you are using a full bridge. If inrush is a problem then you will need to add thermistor to limit inrush.