| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect a load current by eliminating the dead zone region where current cannot be detected according to the input offset voltage of an operational amplifier. SOLUTION: A current detection circuit shifts an input offset voltage Vos of an operational amplifier 11 by connecting a constant current circuit 18 to either input terminal in the operational amplifier 11 for amplifying the potential difference across a shunt resistor 14 being generated due to the flow of a load current IL. Also, a control circuit 4 flows the load current IL with a specific current value Iconst to a motor M as an initial check mode, stores that the value of an input voltage Vm at this time is equal to the load current value Iconst, and calculates a load current value for input voltage Vm based on the stored data. |
