Source Area getting hot.

Could you PLS let me know the turn ratio of the transformer, the output voltage and load current , and the part number of the output diode?

Normally this issue could be solved by the following solutions:

1. Try to use better diode with lower forward voltage drop. So always use schottky diode first, and try to use diode with lower voltage rating. But you always need to meet your dereating requirement.

2. Use a diode with bigger package, to better the theral.

3  Use copper in the PCB as the heatsink. the copper should be attached to the quiet terminal of the diode.

Regards

I am using schottky diode for the same.

Diode is not getting hot and again have placed proper copper area on PCB for proper heat sinking.

Turns ratio of transformer is as per PI design suit.

Output is total 5 i.e. two of them is 22.5-0-22.5  and one is 8 V.

current ratting is 40mA for 22.5-0-22.5 and 120mA for 8 V.

And again i am facing problem in startup.

as supply is not getting started in lower range of input.

It will turn ON on 18VDC but for AC performance is worst.

Please help me. I want to come out from this hell.

Regards.

I misunderstanding your questions. It looks like that your power supply have no thermal issue. For the AC start up issue, I guess it can be solved with input capacitor with higher capacitance.

regards

I have solved startup problem using high capacitance but again inrush current is very high at max input voltage i.e. 38 A at 66V for 500 us.

Now main issure is thermal issue please suggest me how to reduce heat that generated in DPA switch.

switch is getting hot specially source area is getting hot after few minutes.

i have placed around 150 mm^2 of heat sink area on 35 micron pcb layer.

should i increase sink area?

i have already tried with upper version of DPA i.e. 223 and 224 but found no improovment.

thanks for the support.

With regards..!!

It looks like that the switching loss is more important for your case, sincethermal not improved with bigger part. So you can try a new transformer with lower Vor to reduce the switching loss. And more copper attch to the source always helps thermal.

It looks like that the switching loss is more important for your case, sincethermal not improved with bigger part. So you can try a new transformer with lower Vor to reduce the switching loss. And more copper attch to the source always helps thermal.

I have used transformer as per PI expert transformer desing.

Even i have used the core with same AL value.

What changes should i do now?

Secondary diode is also schottky.

And i have added external copper heat sink which gave me better result in my thermal issue.

But secondary diode is getting hot.

And after some time one diode of secodary short ckted.!!

Should i chande diode??

U have suggested diode with lower voltage retting means what?

should i use diode with low PIV(peak inverse voltage)?

Bigger size diodes with higher current rating is a possible solution for your thermal problems, so PLS try it. first.

Norammly, the lower volage diode means lower forward voltage drop of the diode, and thus the conduction loss of the diode can be reduced too. So try to find a didoe with lower forward volatge drop when it conducts. But you have to make sure the the volateg rating of the didoe is high enough for your applications.

if the thermal issue can not besolved with bigger or lower forward voltage drop didoes, then the thermal issue can be solved with heasink.

regards