designed flyback not delivering the required current
Hi,
I have attached the PI optimized design for a dual output 40V/0.5A and 5V/0.5A flyback.Since i wanted the 40 V output regulated i have put the feedback using LTV-816 with a series resistor of 6.8K and TL431 on the 40V output.However the issue is that i am not getting the desired amount of current i.e. 0.5A for a small dummy load. The Topswitch 264 KG IC goes into autorestart as soon as i try extracting full power ie. 40V/0.5A.
Please suggest.!
Comments
Hi,
You mean to say the feedback from auxiliary winding ? which is better ?Also, now i have used the entire secondary for 40V/0.5A and have given the feedback similar to the one shown in the pdf that i have attached. The issue still remains the same. I am not getting 0.5A of current.
Please suggest!
Hi Mithali,
Thank you for using PI product on your design. As for your inquiry, if you say 40V/0.5A you mean the 5V output also have 0.5A load? How high your load can go before it goes to auto-restart? What is your transformer design and what is your input line? Thanks.
Best Regards,
PI-SevenofNine
loading either of the outputs with hogh loads(56K) makes it go into auto-restart as well as loading both together with the same load makes it go into auto-restart.My input is 85-265 VAC.Ill attach the transformer design.
Pls Suggest!
| Attachment | Size |
|---|---|
| Design_for_dual_output.pdf (2.43 MB) | 2.43 MB |
Hi Mithali,
Loading 56K means your loading 700uA for the 40V output and 89uA for the 5V. Pleaase monitor the output voltage using an oscilloscope. Kindly send us the captured waveform. Thank you.
Best Regards,
PI-SevenofNine
A DC line on oscilloscope going high and low (autorestart) .
Pls Suggest!
Hi Mithali,
Where is you location. I will refer you our FAEs near your place. Thank you.
Best Regards,
PI-SevenofNine
Hi Mithali, i am not sure, but give it a try, the secondary output which is stacked and giving the feedback may be creating an issue. I mean on full load the voltage produced on 5v output might increase and device goes in to shutdown retry mode. try to measure the voltage on secondary output. if it is exceeding, redesign feedback ckt. Also it is suggested that feedback should be taken from primary voltage.