A power adapter , comprising: a first rectification unit , configured to rectify an input alternating current (AC) and output a voltage of a first pulsating waveform; and a switch unit , configured to modulate the voltage of the first pulsating waveform according to a control signal; a high-frequency transformer with a primary side and a secondary side, configured to output a voltage of a second pulsating waveform based on the voltage of the modulated first pulsating waveform, wherein the first rectification unit is connected to a primary side of the high-frequency transformer without a primary electrolytic capacitor; a second rectification unit , configured to rectify the voltage of the second pulsating waveform and output a voltage of a third pulsating waveform; a first charging interface , coupled with the second rectification unit without a secondary electrolytic capacitor and configured to be coupled with a second charging interface of a device , wherein the second charging interface is coupled with a battery of the device ; and a control unit , coupled with the first charging interface and the switch unit , and configured to output the control signal to the switch unit , to communicate with the device via the first charging interface to obtain a voltage of the battery when the second charging interface is coupled with the first charging interface , and to apply the voltage of the third pulsating waveform to the battery via the second charging interface when adjusting the duty ratio of the control signal to make a peak voltage of the voltage of the third pulsating waveform to be greater than the voltage of the battery . a first rectification unit , configured to rectify an input alternating current (AC) and output a voltage of a first pulsating waveform; and a switch unit , configured to modulate the voltage of the first pulsating waveform according to a control signal; a high-frequency transformer with a primary side and a secondary side, configured to output a voltage of a second pulsating waveform based on the voltage of the modulated first pulsating waveform, wherein the first rectification unit is connected to a primary side of the high-frequency transformer without a primary electrolytic capacitor; a second rectification unit , configured to rectify the voltage of the second pulsating waveform and output a voltage of a third pulsating waveform; a first charging interface , coupled with the second rectification unit without a secondary electrolytic capacitor and configured to be coupled with a second charging interface of a device , wherein the second charging interface is coupled with a battery of the device ; and a control unit , coupled with the first charging interface and the switch unit , and configured to output the control signal to the switch unit , to communicate with the device via the first charging interface to obtain a voltage of the battery when the second charging interface is coupled with the first charging interface , and to apply the voltage of the third pulsating waveform to the battery via the second charging interface when adjusting the duty ratio of the control signal to make a peak voltage of the voltage of the third pulsating waveform to be greater than the voltage of the battery . <EOS>