| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a PAM (Pulse-Amplitude-Modulation) control type motor capable of being driven stably even in a low voltage although it has a simple circuit structure. <P>SOLUTION: A PAM (Pulse-Amplitude-Modulation) control type motor 1 where a driving voltage Vm changes has a driving device 4 for supplying driving current to a coil 6 through a plurality of current in/out wiring lines 7. The driving device 4 comprises: an upstream side power element 21 and a downstream side power element 22 for switching the current in/out wiring lines 7; a control circuit 31 for applying a control voltage VG to the upstream side power element 21 and the downstream side power element 22; and a control voltage formation circuit 41, which is provided between the control circuit 31 and the upstream side power element 21, for forming the control voltage Vg by dividing the driving voltage Vm. A P-channel MOSFET is used for the upstream side power element 21, and the control voltage formation circuit 41 is provided with a low voltage auxiliary circuit 50 for increasing the control voltage Vg when the control voltage Vg decreases to a predetermined value or lower. <P>COPYRIGHT: (C)2012,JPO&INPIT |
