The reason of EMI problem of DC-DC ?

[walkalways]

dc-dc problems

I have EMI problem at about 100Mhz, i do not known the reason? is because of the rise time of SW node, or the ring of the SW node, in a DC-DC converter chip? anybody can help me , thanks a lot!

 

[dipnirvana]

effect of emi in dc-dc converter

Please share ckt. It can be the resonating frequency of ur transformer/inductor.

 

[Dmitron]

emi problem

the most simple method of decreasing EMI is to increase the resistor in gate. And look the gate voltageform with oscilloscope.

 

[dick_freebird]

emi reason

First check the self-resonant frequency of the inductor, then what the "tank" of inductor and stray+Cout of the switch node might produce. A time domain 'scope
might show you resonant behavior if you look. Also the act of probing, while monitoring the spectrum analyzer to see if the center frequency of the spur moves on contact, can pin down the critical node.

 

[nadigsharma]

why emi problem

If u have not tuned the IFT properly then the EMI effect will come and trimmer capacitor in the circuit can cause EMI more