I need a help about SG3525

dinithm

Member
I made SMPS for a car amplifier,
but there is un expectable spike on it

this is the waveform at IDLE
scope_1.jpeg
1A load
scope_2.jpeg
heavy loads (<3A output)
scope_3.jpeg
this is data of my transformer
transfomer data.jpg

schematic.jpgvaweforme.jpeg

can u pleas tell me ,what is the reason of that matter.and what do I do to resettle this ,
thank you.
 

dinithm

Member
the transformer that I pick from another car amplifier working perfectly instead of my transformer
DSC_0154.jpgscope_4.jpeg

so what can I do for my transformer,

thank you
 

ultra

Member
Since you are using a transformer from another amp, lower the Fosc to around 50KHz and see what happens.
 

angellina

New member

Redwire

New member
Can you post your actual schematic?

I am seeing the MOSFET take a very long time to switch, about 1.5 usec
I would guess problems with the driver, looks like turn ON time is too slow, or way too much deadtime.

Your transformer calc. tool shows 2usec deadtime on 70kHz PWM which I think is too much.
Why 21AWG secondary winding for 4A? Seems a bit thin.

SG3525 can have troubles driving big mosfets, especially if you have no filter between Vc and V.
 
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