Problem with heating of a flyback DC-DC convertor

hi,
i have design a flyback dc to dc convertor using mc34063,
my i/p is 8v dc to 30v dc and three o/ps,
(1)5v (2)24v (3)9v.

now problem is this work fine with inductor,means non isolated dc to dc convertor.
and i can load it up to 1 amp.
but when i am connecting transformer with it for isolation ic is start heating,i tried snubber but didn't work.

so plz some body help me.

bye.

flyback convertor

suresh_ecer said:

hi,
i have design a flyback dc to dc convertor using mc34063,
my i/p is 8v dc to 30v dc and three o/ps,
(1)5v (2)24v (3)9v.

now problem is this work fine with inductor,means non isolated dc to dc convertor.
and i can load it up to 1 amp.
but when i am connecting transformer with it for isolation ic is start heating,i tried snubber but didn't work.

so plz some body help me.

bye.

Click to expand...

Post the diagram so I can have a look at it...

design a flyback

It may be the problem with your transformer design.

What i could understand is that the reflected voltage from secondary to primary, and the leakage inductance is playing an important role.
Try to minimize leakage inductance.

What is the primary inductance of your transformer.

If it is low then the peak current through the transformer primary increases, if it exceeds the peak current limit of the device it can really have a bad effect

Place a small resistor between source terminal and ground and measure the peak current .
Best of luck

mc34063 flyback

hi meridian & saurav
thanks for taking interest in my project.
i am sending my project's schematic and transformer specification.
so plz check it and replay me if u want any other information.
bye.

Re: mc34063 flyback

suresh_ecer said:

hi meridian & saurav
thanks for taking interest in my project.
i am sending my project's schematic and transformer specification.
so plz check it and replay me if u want any other information.
bye.

Click to expand...

thank for your project,but i don't know about value of R7 in your schematic.And can you show me mind of line:
primary = 15 turns #14 AWG
#14 AWG is what?
sorry about my english!!!