this is our Piezoelectric speakers Part number BPR2207H0-F2,I use a lithium battery to power the evaluation board 48580 and then add an audio signal to the 48580 signal input. The piezoelectric speaker is connected directly to the output of the EV kit 48580. The oscilloscope now measures the power supply (VDD) of the evaluation board (the output interface of the lithium battery), The measurement results still have a large amount of power supply ripple。