A voltage converter for medical devices includes a switch capacitor converter core including a plurality of power transistor switches configured to receive an input voltage and output an output voltage; a switch driver connected with the switch capacitor converter core and configured to turn on corresponding power transistor switches in the switch capacitor converter core so as to supply power to a load receiving the output voltage; a switch signal router connected with the switch driver and configured to selectively transmit signals required by the switch driver; a gain selection decoder connected with the switch signal router; a gain controller connected with the gain selection decoder, the gain selection decoder being configured to decode gain selection instructions transmitted from the gain controller; an input adjusting device connected with the gain controller and configured to receive the input voltage and a reference voltage, to indicate relationship between the input voltage and the reference voltage, and to transmit the relationship to the gain controller; and an output adjusting device connected with the gain controller and configured to receive the output voltage and the reference voltage, to indicate relationship between the output voltage and the reference voltage, and to transmit the relationship to the gain controller.