I am using this buck converter.
Buck Converter Specifications :
- Input Voltage - 18V to 32V
- Switching Frequency - 300kHz
- Output Voltage 9V
- Load Current - 0mA to 200mA Maximum.
When measuring the switching frequency using an oscilloscope, I am placing the probe directly on the TP1102 and also measuring the output voltage on the 47uF capacitor pad.
I got the below waveforms :
Input voltage of 14V:
However, with the same input voltage, I am just removing the probe which was placed at the switching frequency node. Now, I didn't observe the ringing.
Input voltage of 14V without probing the switching frequency :
As you can see, the ringing vanished once I disconnected the probe.
Can someone tell me how this ringing at the switching frequency node is happening even though I am probing at the TP1102 and how this is coupling at the other probes also?
Please also provide a solution on how to avoid this ringing while measuring the values.
Below is the ringing frequency: