A switching voltage converter, suitably a boost converter, employs an n-type transistor, preferably an NMOS FET, as a series switch, with its drain coupled to the cathode of the converter's diode and its source coupled to the converter's output node. A charge pump driven by the converter's switching voltage provides a voltage V.sub.on at the NMOS FET's gate input sufficient to turn the FET on. A series switch controller is arranged to, in response to a control signal, hold the NMOS FET off such that the converter's output voltage V.sub.out is approximately zero regardless of the status of input voltage V.sub.in, or allow the NMOS device to be turned on by V.sub.on.