Hi Yunkai, Thanks for providing the scope shots. Here are a few things to consider. What are you driving VIN with? Probe VIN and share waveform. Even though it is a DC signal, I think it is getting "hammered" by the capacitance of the switching caps. This is an unbuffer input, so I would try adding a small series resistance (like 50 ohms). Does this help? Additionally, you can add a capacitor to ground to create a low pass filter. Reduce VRT to 1.2V and scale the VIN. Does this still occur? Best Regards, Dan
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