Ringing in flyback PS.
I have a 120W power supply with the below specifications:
Vin: 300Vdc (regulated dc voltage from a Boost PFC stage)
Vout:12V
Iout: 10A
PI device: TOP257EN (eSIP)
Switching frequency: 132kHz
Flyback topology, with primary inductance = 339uH and primary leakage inductance = 5uH.
RCD+Z clamp used. R=15k, C=4.7nF, D=ES1J (Ultrafast)and Z=P6KE200A.
Vor=120V
Vclamp = 188V
All component values above are taken from PI expert design solution.
Problem: The drain waveform is ringing at 6MHz.
I designed an R-C snubber, where R=200 ohms and C=1nF. However, the calculated power dissipation across R turns out to be 23W!
Question: How do I eliminate or reduce the ringing? Is there any other method other than using RC-snubber?
Thank you in advance.
Regards
S.Prashanth
Comments
Hi pavan.kumar,
The circuit won't get damaged it will just auto-restart at reverse polarity test.
Regards,
PI-Pike
Hai , I Have a doubt in the above circuit i am using TOP261YN IC PACKAGE . IN AN 43 page no:20 figure:22 shows different layout X, G pin not connected to ground . in my circuit i connected directly to ground . pls explain me clearly how to connect top261YN Y package in my circuit .can i connect as per the an43 application note. pls replay me its urgent for me
Hi pavan.kumar,
If it is 261YN package you are required to do figure 22, to improve noise immunity.
Regards,
PI
Hai,
in the above design .when i connected 2.8amps load, 60v output, ,230vac . transformer temperature going 90deg. topswitch ic going 80deg snubber circuit temperature aslo going high. after 1hour going to shutdown. i arranged this circuit in closed enclouser with 12v cooling fan connected. and heat sink also increased. please tell me how to slove transformer temp and topswitch temp and snubber circuit temp. i am struck to slove this problem . i designed the transformer as per the pi expert.
Hai, i am confused please tell me TOP261YN Ypackage switching frequency. and in PI online this packages are not showing. may i use this TOP261YN Package instead of TOP262EN With 132kz frequency. pls quick replay
pls replay me for 56 post
Hi pavan.kumar,
The switching frequency of TOP261YN is fixed internally, it is 66kHz.
Regards,
PI-Pike
And also i want to do reverse polarity test . To do this tests what precautions have to take. pls suggest me
- can you please tell me how this test is done?
---> This test is done by reversing the output terminals to the battery. if i connect output reverse to the battery. it should not damage the circuit .