| 摘要 |
PROBLEM TO BE SOLVED: To adapt the voltage polarity of a detection signal to a polarity for a post stage circuit system and make it difficult to have noise superposed on the detection signal. SOLUTION: A resistor R1 for detection is connected in series with a power line and a reference voltage source 8, which has its negative-electrode terminal grounded, is provided. A series circuit of resistors R2 and R3 is connected to one end (B) of the resistor R1 for detection and a series circuit of resistors R4 and R5 is connected to the other end (A) of the resistor R1. The other end of the resistor R3 and the other end of the resistor R5 are connected to the positive-electrode terminal of the reference voltage source, and a voltage signal appearing at the connection point between the resistors R2 and R3 and a voltage signal appearing at the connection point between the resistors R2 and R3 are biased with the reference voltage obtained by the reference voltage source 8. The two voltage signals which are biased are inputted to the input terminals of an error amplifier EA, and the obtained output signal is regarded as a detection signal corresponding to the current flowing in the power line.
|
