Patent ID: 7369383
Filing Date: 2008-05-06
Classification: H02H

Abstract:
1. A circuit for protecting an electronic motor control unit, the circuit comprising: a signal connection receiving and/or emitting an electrical signal, a switching element which controllably couples and decouples the signal with an electronic motor control unit connection, wherein the switching element is controllable via a control input, a control circuit, the input side of which is connected to the signal connection while the output side thereof is connected to the control input of the switching element in order to open or close said switching element according to the electrical state at the signal connection, wherein the control circuit has a hysteresis characteristic regarding the electrical state at the signal connection, an error signal output connected to the output side of the control circuit, and wherein the control circuit comprises a threshold value unit to open said switching element if the input voltage exceeds a preset switch-off voltage and to close said switching element if the input voltage does not reach a preset switch-on voltage in which case the switch-on voltage and the switch-off voltage are different, the threshold value unit comprises an operational amplifier and a feedback resistor to generate the hysteresis characteristic, and wherein the signal connection is coupled with a sensor output and the inverting input of the operational amplifier is connected to a reference voltage source.