| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an inexpensive current-sensing circuit with high current-sensing accuracy. <P>SOLUTION: A current-sensing circuit 1 includes: a shunt resistance R1 connected in series with a current path from an inverter 106; an operational amplifier 12 that amplifies the voltage across the terminals of the shunt resistance R1 by a prescribed amplification factor; a low-pass filter 18 that averages the output voltage from the operational amplifier 12; and an arithmetic unit 50 that, on the basis of the output voltage from the low-pass filter 18, calculates the current flowing through the current path. The power-supply voltage of the operational amplifier 12 is set higher than the power-supply voltage of the arithmetic unit 50, and the low-pass filter 18 averages the output voltage from the operational amplifier 12 to a level lower than the power-supply voltage of the arithmetic unit 50. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
