Patent ID: 7675726

Claim:
A device for protecting an electronic module disposed in a control device in a multi-voltage on-board electrical system having an accumulator with a low on-board electrical system voltage against short circuiting to a high on-board electrical system voltage, comprising: a MOSFET transistor having a drain source path inserted between a control device connection and a connection of the electronic module, and with: a source connected to the connection of the electronic module; a drain connected to the control device connection; and a gate; a Zener diode connected between said gate and said source of said MOSFET transistor; a gate resistor connected between said gate of said MOSFET transistor and a positive pole of the first accumulator; and a diode connected in parallel with said gate resistor, for conducting current in a direction from said gate to the positive pole of the accumulator; wherein when a short circuit to the high on board electrical system voltage is conducted to said drain, said MOSFET transistor turns on or remains turned on; and wherein said MOSFET transistor has a threshold voltage and, in an event of a short circuit to a highest voltage of the on-board electrical system active at the device connection, a source voltage of said transistor is limited to a value Vs=Vbat 1 −Vth, where Vs is the source voltage, Vbat 1 is the low on-board voltage, and Vth is the threshold voltage of said transistor.