Patent ID: 7218497
Filing Date: 2007-05-15
Classification: H04B,H04L

Abstract:
1. A protective circuit for protecting a CAN bus transceiver against overvoltage, wherein the CAN bus transceiver is configured, in voltage terms, for a first vehicle electrical system, and the CAN bus transceiver is operated in a second vehicle electrical system having a voltage multiple times a voltage of the first vehicle electrical system either alone or in a two-voltage vehicle electrical system with the first vehicle electrical system and the second vehicle electrical system, the CAN bus transceiver having two bus terminals for connection to respective bus lines and a supply voltage source of the transceiver with a positive terminal and a negative terminal, the protective circuit comprising: two diodes connected between the bus terminals of the transceiver, said diodes having cathodes connected to one another and to a predefined potential; a limiting resistor connected between each bus terminal of the transceiver and the bus line assigned thereto; and a first current-mirror circuit connected between the positive terminal of said supply voltage source of the transceiver and the first bus line, and a second current-mirror circuit connected between the second bus line and ground, for restoring voltage levels reduced by said limiting resistors on the bus lines.