For a self- drive buzzer ( DC/ circuit- built), either pizeo or magnetic just apply the rated current and voltage.

 For the external-drive buzzer, it depends on,

1. We should give magnetic buzzer 1/2 square wave, and provide it at least 3 times the amount of the rated consumptive current.

2. Otherwise, we give square wave to the peizo buzzer instead of 1/2 square wave, because the half wave might cause the buzzer does not work.

Therefore, voltage control is an important factor for a peizo buzzer which is driven by the voltage.