| 摘要 |
PURPOSE:To keep the current flowing to the load within the specified limits for any input of chopping frequency driving signal. CONSTITUTION:A current control circuit 2 changes the output in accordance with the frequency of chopping actuation. In a proper chopping actuation, the voltage VR2 is inputted to the terminal of a comparator IC3 which is decided by the partial pressure ratio between resistances R3 and R2 connected in parallel and a resistance R4 connected in series. In the meantime, when the current value is below n-times in which it is impossible to actuate the chopping, the voltage inputted to the comparator IC3 is decided by the partial resistances R3 and R2, so that the value will rise as compared with the case in the abovementioned chopping actuation. On this account, when it is impossible to actuate the chopping by high speed operation, the increase of supply current to a coil L is ensured and the sufficient torque can be obtained without fail. |
