| 摘要 |
PROBLEM TO BE SOLVED: To prevent failure when a single phase is open-circuited by providing a control part for stopping drive operation by detecting the open-circuiting when the single phase is open-circuited. SOLUTION: If an A-phase transistor or an FET is turned off when a B phase is not connected, energy being accumulated in the A phase cannot be discharged since A-phase OFF current does not flow. Therefore, a voltage that is several times larger than a power supply voltage can be maintained until a next drive on. When a voltage divided by voltage-dividing resistors 1B and 1C is larger than a voltage that is set by Vref 2 by detecting the voltage, the output of a comparator 1A changes. The noise of the output is eliminated by a noise filter 19, and continuation time after change by a counter 18 is counted. When the continuation time exceeds a set amount of time, it is set to a latch circuit 17, drive is turned off and resetting is made, and a drive operation is stopped until drive on. |
