| 摘要 |
PURPOSE:To achieve highly efficient cooling and to lengthen service life of a cooling fan, by controlling the operating time of the cooling fan according to the load condition of device. CONSTITUTION:A current-voltage conversion circuit 2 detects load current I flowing through a load device 5 connected with a power source 4 and converts the load current I into a voltage value V which is fed to an output terminal C. A timer circuit 1 varies the ratio between ON and OFF intervals with the voltage value V and operates a cooling fan 3. In the current-voltage conversion circuit 2, there is an approximately proportional relation between the load current value I and the converted voltage value V. The timer circuit 1 is set such that the ratio between ON interval and the entire interval at an output B is higher for higher voltage value V inputted to an input terminal A. |
