Patent ID: 7119508
Filing Date: 2006-10-10
Classification: G11B,H02M,H02P

Abstract:
1. A rotation drive system for a direct current motor including: a direct current motor; output MOS transistors for making desired currents flow into coils of the direct current motor; and a motor drive control device for rotating a rotor, which detects currents flowing into the coils of the direct current motor, compares with a demand current, determines an amount of currents to be made to flow into the coils of respective phases by the output MOS transistors, and in order that the output MOS transistors make the amount of currents flow, controls pulse widths of control signals to supply to drive circuits of the output MOS transistors, wherein the motor drive control device comprises: current sensing MOS transistors having a predetermined size ratio to the output MOS transistors, in which source terminals thereof are commonly coupled to source terminals of the output MOS transistors, and to gate terminals thereof are applied signals identical to signals being applied to gate terminals of the output MOS transistors; and a voltage applying circuit that monitors drain voltages of the output MOS transistors, and applies voltages identical to the drain voltages to the drain terminals of the current sensing MOS transistors.