Patent ID: 6901520

Claim:
A computer system comprising: a battery for supplying electrical power over a power line; data processing circuitry connected to said power line and supplied with electrical power by said battery, said data processing circuitry having associated therewith a withstand voltage value above which at least a portion of said data processing circuitry is not designed to operate; a terminal connected to said power line, for connecting said computer system to at least one external device over a bus; system protection circuitry connected to said power line, disposed between said data processing circuitry and said terminal, for protecting the data processing circuitry from voltages greater than said withstand voltage value caused on said power line by said at least one external device; the system protection circuitry comprising: a diode provided in said power line, said diode limiting a flow of electric power to one direction; a voltage sensor for detecting voltage values of said power line at said terminal and, switching means, responsive to a detection by said voltage sensor of a voltage value greater than a predetermined value, which predetermined value is less than said withstand voltage value, for disconnecting said power line, and responsive to a detection of a voltage value lower than said predetermined value to connect said power line, wherein said switching means includes a limiting element for supplying a predetermined electric power value in a direction opposite to said one direction when said power line is disconnected.