SYSTEM AND METHOD FOR SWITCHING VOLTAGE

A device and method for providing varying bias voltages to a security device in a cable set-top terminal, comprising a receiving unit in the security device for receiving replaceable conditional access cards, a card interface for sensing the insertion of conditional access cards in the receiving unit and outputting an enable signal to a logic unit, and the card interface for identifying a bias voltage of the conditional access card and outputting a request of the bias voltage to a controller, a controller for receiving the request of bias voltage from the card interface and outputting a selection signal of the bias voltage to a logic unit, the logic unit for receiving the enable signal from the card interface and selection signal of the bias voltage from the controller to output a control signal to a switch, and a switch for receiving a control signal from the logic unit and providing a switched voltage to the security device based on the selection signal from the controller.