The invention relates to voltage converting supply units for electronic terminals. Said invention particularly relates to a plug-in socket for coupling corresponding standard connectors and connecting an electronic terminal to a voltage supply device. A voltage-converting unit for a plug-in socket is also disclosed. The aim of the invention is to improve the use of the voltage converting supply units with regard to the state of the art. Said aim is attained by the plug-in socket according to claim 1, voltage conversion units according to claim 12 and electronic terminals according to claim 14.