| 摘要 |
PURPOSE:To reduce power consumption by enabling a pattern FG and a pattern FG to be used selectively without providing an exclusive terminal. CONSTITUTION:This circuit is provided with a comparator 36 which compares the potential at the input terminal FGIN of a pattern FG with Vref 2. The voltage Vref 2 is set enough higher than the reference voltage Vref 1 of an FG amplifier 38 related to the pattern FG. The output of the comparator 36 is used as an FG signal changeover signal FGSW. In case that the output of the comparator 36 is an L value, the FG amplifier 38 is turned on, and a switch 22 falls to the side of B. In case that it is an H value, the FG amplifier 38 is turned off, and the switch 22 falls to the side of A. The FG signal to be supplied to a speed control circuit 16 can be changed over from an FG pattern to a hall FG by pulling up the input terminal FGIN of the pattern FG. At that time, an excessive current does not flow through a diode Q1. |
