Patent ID: 7617019

Claim:
A ventilation device for ventilating boards mounted in a support unit, the ventilation device comprising: at least one fan unit connected to a power supply unit by connecting wires; a control unit for monitoring and regulating the at least one fan unit, wherein the control unit controls a control element arranged in a power circuit of the connecting wires, wherein the control unit provides alarm or control signals for transmittal over a bus including signals indicative of an alarm condition relating to increased rotational speed or noise in the fan unit; and temperature monitoring and switching circuitry including a temperature monitoring device and a switching device connected in parallel with the control element, the circuitry configured to detect and respond to a fault in the fan unit by bypassing the control unit and through-connecting the switching device to power the fan unit at full operating voltage when a board temperature is greater than a board limit temperature, the temperature monitoring device comprising a sensor diode integrated in an integrated circuit of an electronic component of the respective board.