snubbing output ringing....
To whom it may concern...
I have a +/-15V output flyback supply using the TNY263 as the controller.
A ringing component at 4-10MHz is bypassing all of my secondary filtering and linear regulators and corupting my A-D conversions if the burst happens to align with the capture time. (blue primary yellow problematic HF ringing secondary)
The only way to mitigate this is to use a series RC across the output diodes correct?
Should each seconday coil be measured for inductance so that the cap and resistor is chosen to be near critically damped, and have a time constant to mostly discharge before the next 132KHz burst cycle (~7us)?
Best regards,
Matt.
Comments
Thanks PI...
now I no where my heavy 10MHz conducted emission spike was comming from last revision. LOL
The primary coils (900KHz) ring out can only be somewhat attenuated by the bulk capacitors and line EMI filter correct?
The last time it was necassary to place a metal sheild over most of the switcher and ground it back to the flyback transformer....
The EMI was eminating directly from the transfromer and regenerating on the lower stacked PCBA?
Matt,
Can you provide me with a schematic please?
The D3 and D2 have a 47p 340R across them... 10MHz ringing gone after diodes!
The AC filter is now on the lower board two 0.1Ycaps and a 22mH CM then a .1Xcap (cookie cutter EMI filter)
the +/-15 have 200uF each on them to ground... sorry the clipped top coil is my proprietary HV charge pump (loading such high 100Kohm trickle impedance not so worried about it)
The D3 and D2 have a 47p 340R across them... 10MHz ringing gone after diodes!
The AC filter is now on the lower board two 0.1Ycaps and a 22mH CM then a .1Xcap (cookie cutter EMI filter)
the +/-15 have 200uF each on them to ground... sorry the clipped top coil is my proprietary HV charge pump (loading such high 100Kohm trickle impedance not so worried about it)
Matt,
I am assuming that you do not have a snubber across the secondary diode at present. I would recommend you use PI Expert for more help with the snubber.