WATCHDOG CIRCUIT PROVIDING A TEMPERATURE-DEPENDANT SIGNAL FOR A MICROCONTROLLER OF AN ELV

摘要

The invention relates to an actuating circuit for an ELV of a motor vehicle, comprising a microcontroller (6) for controlling a motor drive (1) and a watchdog circuit (7). An input (9) of the microcontroller (6) is coupled to a first output (8) of the watchdog circuit (7), an output (10) of the microcontroller is coupled to an input (13) of the watchdog circuit, and a reset input (15) of the microcontroller is coupled to a second output (14) of the watchdog circuit. The microcontroller is configured such that, after receipt of an impulse at the input (9), it emits a response signal at the output (10) within a first predetermined time interval. The watchdog circuit (7) is configured such that, if after the output of an impulse at the first output (8) thereof within a second predetermined time interval, which is longer than the first predetermined time interval, it receives no response signal at the input (13) thereof, it emits a reset signal at the second output (14) thereof. The watchdog circuit is furthermore designed such that it emits an impulse sequence at the first output (8), wherein at least one parameter of the impulse sequence is dependant on an ambient temperature of an element of the watchdog circuit. The microcontroller evaluates the at least one parameter of the impulse sequence received at the input (9) thereof such that a value for the ambient temperature is obtained, wherein the microcontroller controls the ELV as a function of the obtained value for the ambient temperature.