Current-sensing circuit and air-conditioning device provided therewith

摘要

Disclosed is a current-sensing circuit (1) provided with: a shunt resistance (R1) connected in series with a current path from an inverter (106); an op-amp (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 op-amp (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 aforementioned current path. The power-supply voltage of the op-amp (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 op-amp (12) to a level lower than the power-supply voltage of the arithmetic unit (50).