Granted Patent B2

US 7,511,606 · App. 11/131,846 · Granted Mar 31, 2009

Abstract

Claims (11)

1. A vehicle locating unit comprising:

a receiver for receiving a signal from a network of communication sources;

a transponder activated when a communication source sends a message to the receiver;

a power supply regulating circuit for regulating a nominal vehicle input voltage and powering said receiver and said transponder; and

a protection circuit responsive to an injected input voltage at least an order of magnitude higher than the vehicle input voltage and configured to clamp the injected input voltage at a predetermined maximum voltage the same as or approximately the same as the vehicle input voltage, the protection circuit comprising:

a filtering circuit with at least one voltage protection device having a breakdown voltage at least as high as the injected input voltage, and

a voltage regulating circuit including at least one voltage protection device having a breakdown voltage at least as high as the injected input voltage.

2. The vehicle locating unit of claim 1 in which every component of the protection circuit is selected to withstand an injected input voltage greater than said nominal input voltage.

3. The vehicle locating unit of claim 1 in which the protection circuit includes a voltage limiting diode which clamps the injected input voltage at the predetermined maximum voltage.

4. The vehicle locating unit of claim 1 in which the protection circuit is integrated with the power supply regulating circuit.

5. The vehicle locating unit of claim 1 in which the power supply circuit further includes a second stage voltage regulating circuit connected to the first stage voltage regulating circuit and configured to provide the appropriate voltage levels to the receiver and transponder.

Assignments (20)