Some Problems about 24 VDC - 3 A Power Supply
Dear Advison
I am a member of R&D section of Afratab Group. we produce LED lamps and for our new project we decide to use your products. I downloaded your supporting documents and PI Expert softwear.by using them and our store, TOP250 and EI35 was chosen for realization. the circuit is demonstrated and we got 24V in off load and low load cases but as we put some smaller loads like 22 ohms the circuit can not work correctly and the output voltage waveform deformed to something like what is in the attached picture. It seems that the charge time of output capacitor is not appropriate with the on/off time of Transformer. I try to correct this problem with changing the capacitor on control pin because i thought this capacitor can change the on/off time of topswitch. the circuit did not work when i put smaller capacitors (C < 47uF, like 22uF) and it works terribly while i put bigger capacitors ( C > 47uF, like 330uF).In addition, this circuit did not give more than 1A yet. thus, I could not get 3A from this circuit yet. could you please help me to solve this problem and reach the full load operation.
thank you
with the best regards
Pooria Saiyad Khodashenas ( khodashenas@afratab.com )
Comments
Thank you for your response.
The PI's 24V/75W recommended circuit was used which downloaded from PI's LED section. Indeed, I think the main problem is the transformer because the recommended transformer has an EER28 core while we have EI25 and I think I could not change parameters correctly. could you please help me in this case.
meanwhile, I try to design my own schematic using PI Expert softwear. finally only 24V/2.66A has been gotten from it since 3.15A was needed in output. As it mentioned above I think the problem is transformer. Indeed, It is my first design and I need some help to handle it. I will attach the PI Expert File for you.
thank you so much.
best regards
pooria
Please send me a copy of your schematic (in a PDF format) and the design file from PI Expert. It would help to have scope photos of the drain voltage and drain current.
Z. Cochrane