| 摘要 |
PURPOSE:To make it possible to detect current without requiring any reverse- current blocking diode by arranging power Darlington transistors(PT) on the lower side arm of an H bridge such that no current flow through parasitic diodes on a chip thereby employing such PTs as having no apparent parasitic diode. CONSTITUTION:Upon turn ON of a PT 17, current flows from + terminal of power supply through a FET 4, winding 1 of a motor, a PT 17 and a current detecting resistor 12 to the ground of power supply. Upon turn ON of a PT 16, current flows through a FET 5, the winding 1, the PT 16 and the current detecting resistor 12 to the ground of power supply. In other words, the PTs 16, 17 are turned ON/OFF to invert the direction of current flowing through the winding 1. At the instance of turn OFF of the PTs 17, 16, energy stored in the winding 1 is regenerated through parasitic diodes of the FETs 4, 5 to the power supply and fed from the ground through circulation diodes 10, 11. Consequently, only the winding current is detected. |
