A two stage multiple output power supply device is capable of outputting
programmable DC voltages onto multiple outputs. The first stage receives
an AC supply voltage and outputs a DC supply voltage. The second stage
includes a DC-ID controller and multiple DC-to-DC converters, each
DC-to-DC converter receiving the DC supply voltage and capable of
outputting a programmable DC voltage onto a conductor of a power cord to
power an electrical device. For each DC-to-DC converter, the DC-ID
controller receives information in an AC signal on the conductor, the
information indicating the voltage and current requirements and the
polarity of an electrical device connected to the power cord for that
DC-to-DC converter. In response to the information, the DC-ID controller
controls the DC-to-DC converter to set a magnitude, a polarity and a
current limit for the programmable DC voltage that will be output by the
DC-to-DC converter.