Vehicle locating unit with input voltage protection

• US 20060261934A1
• Filed: 05/18/2005
• Published: 11/23/2006
• Est. Priority Date: 05/18/2005
• Status: Active Grant

• Current Assignee: Calamp Wireless Networks Inc. (CalAmp Corporation)
• Original Assignee: LoJack Operating Company, LP (Solera Holdings Incorporated)
• Inventors: Nguyen, Son, Rhodes, Jesse, Stroud, Ian Christopher, Smithers, Colin Richard, Finchley Cletheroe, Daniel Jonathan, Howe, Timothy David, Smith, Gerard Edward, Watson, Nigel James, Krishna, Sampath, Romano, Frank, Greendale, Steven Walter, Crewe, Philip Grahame, Marsden, Mark
• Granted Patent: US 7,511,606 B2
• Time in Patent Office: Days
• US Class Current: 340/428
• CPC Class Codes: B60R 25/102 a signal being sent to a remote location, e.g. a radio signal being transmitted to a police station, a security company or the owner
• CPC Class Codes: B60R 25/33 of global position, e.g. by providing GPS coordinates

Abstract

A vehicle locating unit with 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, and a power supply regulating circuit for regulating a nominal input voltage and powering the receiver and the transponder. A protection circuit is responsive to an injected input voltage and configured to clamp the injected (high level) input voltage at a predetermined maximum voltage.

Claims

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 input voltage and powering said receiver and said transponder; and

a protection circuit responsive to an injected input voltage and configured to clamp the injected input voltage at a predetermined maximum 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 4 in which the power supply regulating circuit includes a filtering circuit connected to the input voltage and a first stage voltage regulating circuit connected to the filtering circuit.

6. The vehicle locating unit of claim 5 in which the protection circuit is integral with the filtering circuit and the first stage voltage regulating circuit.

7. The vehicle locating unit of claim 6 in which every component of the filtering circuit is chosen to withstand an injected input voltage greater than said nominal input voltage.

8. The vehicle locating unit of claim 7 in which the first stage voltage regulating circuit includes a voltage limiting diode which clamps the output of the filtering circuit to said predetermined maximum.

9. The vehicle locating unit of claim 8 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.