I ordered a sample of TPS54239.
My requirements are:
Input 12V; Output 5V; Imax = 1A
For testing purposes I soldered all required components together on a little board. All connections as short as possible (e.g. VFB). All grounds connected without a ground plane. Now I can see a repetitive disturbance on the 5V Output Voltage (see attachment). The periodic time between the ringing is 2us and the signal itself has a time period of 7,5ns.
What is the reason for this disturbance?