| 摘要 |
PURPOSE: To improve the sensing accuracy of each Hall-element in respect to the variation of its ambient temperature, when the rotational position of a rotor is sensed by the constant-current drive of InSb based Hall-elements. CONSTITUTION: To InSb based Hall-elements 18a-18c, power-feedings are performed with constant-current in the state of them being connected in parallel with each other from a DC power supply terminal VC via current limiting resistors 19, 20. A series circuit comprising diodes 21a, 21b is connected in parallel with these Hall-elements 18a-18c, and thereby, the currents fed to them are shunted. The Hall-constant of each Hall-element is lowered with its ambient- temperature-rise, but the shunted current component of the diodes comes to flow through it with the reduction of its input resistance, and as a result, the reduction of the sensed voltage of each Hall-element can be suppressed. Also, by the reductions of the Vfs of the diodes, the self-heat-generations of the Hall- elements can be suppressed. |
