| 摘要 |
PROBLEM TO BE SOLVED: To detect the flow of current of an inductive load for generating a voltage signal which is directly proportional to the mean value of a current circulated in the load, without being subjected to the effects of an output change at a power amplifying stage. SOLUTION: A signal existing in a current-detecting resistor Rs connected to load is amplified by a sense amplifier by using a pair of complementary periodic reference signals, and an amplified signals displaying a current in the load to be supplied to an error amplifier, which drives a power amplifier at a bridge stage is generated, thus monitoring a current lowering through the inductive load LOAD driven through a power amplifying state in a PWM mode. A load current is sampled by a sample-holding circuit containing a sampling switch SW and a capacitor Csh for storage in the method. The mean value of the load current is monitored by closing the switch by synchronized pulses, coinciding at the midpoint of an active period and the midpoint of a current recirculating period and sampling the load current at these midpoints. |
