Patent ID: 9030792
Filing Date: 2015-05-12
Classification: H01L,H02H

Abstract:
1. An overvoltage protection circuit for a vehicle, the circuit comprising: a circuit board; a semiconductor device attached to the circuit board and coupled to a supply voltage, the semiconductor having an output, which requires protection from signals applied to said output that have a voltage greater than the supply voltage; a three-terminal field effect transistor (FET) attached to the circuit board, and configured to provide over-voltage protection to the output of the semiconductor device, the FET having a source, which is coupled to said semiconductor device output, the FET having a drain, the voltage of which is susceptible to being provided a voltage that is greater than the supply voltage and, the FET also having a gate, which is coupled to the supply voltage through a resistor having a first side coupled to the gate and a second side coupled to the supply voltage; an electrical load, that is away from the circuit board and which is configured to be driven by the semiconductor device; an electrical conductor, extending between and electrically connecting said drain to said electrical load, at least a portion of the electrical conductor extending through at least a portion of a conduit in the vehicle, said portion of the conduit in the vehicle being away from the circuit board and having therein, the electrical conductor and at least one other conductor having an over-voltage, the over-voltage being a voltage having a magnitude that exceeds the magnitude of said supply voltage and which if connected to the output of the semiconductor device would damage said semiconductor device; a voltage comparator attached to the circuit board, the voltage comparator, having first and second inputs and an output, the first input being electrically coupled to the electrical conductor, the second input being coupled to the supply voltage, the output being coupled to the second side of the resistor and thereby coupled to the gate, the comparator being configured to generate an output voltage that turns the FET on as long as the first input voltage is less than the supply voltage; whereby an over-voltage on the electrical conductor provided by said at least one of said other conductors causes the voltage comparator output voltage to shut off the FET and thereby prevent an overvoltage on the electrical conductor from reaching the output of the semiconductor.