TIDA-01494: Ripple Noise, Power limitation.

Hi, Kim

1st case:

please limit your probe bandwitdh to 20MHz, and use the minmized probe loop, to do the test. 

If this spike still exsit, please check your feedback loop, to see what happens in mistake.

2nd case:

I guess the feedback is limited by output current, please enlarge the current limitation in the feedback circuits.

Hi,

please refere to the following for your ripple test method. 

How to measure ripple for better design outcomes

Testing switching power supplies includes many different tests, one of them being the output-voltage peak-to-peak ripple. Output-voltage ripple is the alternating current (AC) component of the direct current…

By George Lakkas over 9 years ago in Technical articles > Power management

And if you still see the voltage spike, please extend the waveform for the detail, let's see its osc frequency.

Hi,

Your waveform show an high frequency oscillation, this is large possible introduced by switching of MOSFET. 

Please check all the MOSFET Vds voltage, and using snubber absorb it.

And, there is 100kHz swiching frequency ripple. It need you to reduce the ESR of filter cap, you may use more ceramic capacitors to suppress it.

Hi, Kim

This is what I have from our designer. please refer.

750343657,Rev02 datasheet, UCC256301,24V20A,ETD44,TIDA-01494.pdf

Hi, Nick

The infomation you asked is kept by Wurth, we do not have this infomation, because the designer do not leave this to us.