Patent ID: 7720546

Claim:
A closed system having dual power supply switching circuitry, comprising: an implantable medical device (IMD) disposed interior of a boundary; an internal power source for powering the IMD; an external device separated from the IMD by and disposed exterior to the boundary, the external device being in telemetric communication with the IMD and generating an external RF energy source during telemetric communication with the IMD; and passive power switching circuitry for switching from the internal power source to the external RF energy source during communication from the external device to the IMD when power supplied by the external RF energy source exceeds that required for powering the IMD; wherein the power switching circuitry includes a first diode electrically connected to draw power from the external RF energy source, and a second diode electrically connected to draw power from the internal power source; wherein the power switching circuitry further comprises a leakage current path via a switch connected in series to a resistor whose resistance is lower than that of the internal power source, wherein in the presence of an external RF voltage when the switch is closed, leakage current flows through the resistor rather than the internal power source.