TIDA-01494: Ripple Noise, Power limitation.

Hi, Nick

Switching noise generally is exsiting in switching power supply, and it may not big problem as long as it is well treated.

What is your problem here, UCC25640-3 is not operating, or the noise disturbed something?

Hi Desheng Guo,

I think UCC25640-3 is working well. As you see the waveform, the ripple volt is almost max 1V. 

as you mentioned, the noise affects other devices.. so we have to catch the problem.. 

Regards,

Nick. 

Hi Desheng Guo,

After UCC25640-3's BW Pin (C20) capacitor is changed to the 100pF. the output ripple is a little bit improved.. 

the ripple voltage is almost max 664mV..

I'm struggling to find out the way to remove it. would you give us the advice..?

Regards,

Nick. 

Hi,

I'm measuring the ripple waveform.

The below image is shown to the ref. measurement. (47uF,0.01uF are connected.)

The below image 

- Test point : SW line(current) and Q2 gate (load 18A)

I think that the ripple noise occurs under the conditions of ZVS.. 

Any advice?

Regards,

Nick. 

Hi,

I know that the noise is coming from AC. 

After separating gnd_earth(ac) and thermal plate, the noise disappears.

the thermal plate is connected to the FET of the transformer.

I think we need the way to separate them.

Thanks

Regards,

Nick. 

Hi, 

There is no noise if not connecting the cassis ground. 

It seems like the common mode noise. 

Let me know how to remove the common mode noise 

Regards,

Nick.