Patent ID: 7518413
Filing Date: 2009-04-14
Classification: G01R,H02M,H03F

Abstract:
1. A current detection circuit comprising: a current detection resistor configured to generate a voltage between two ends which corresponds to current flowing through the resistor; a first capacitor having one end configured to input an upper end voltage and a lower end voltage of the current detection resistor which are supplied via first and second switches; a third switch configured to selectively supply a reference voltage to the other end of the first capacitor; and an operational amplifier configured to input a voltage corresponding to an electrical potential of the other end of the first capacitor via a negative input terminal, input the reference voltage via a positive input terminal, and generate an output representing a difference between two inputs, wherein the circuit performs an operation for charging the first capacitor with a voltage corresponding to a difference between the lower end voltage and the reference voltage in a state where the first and third switches are turned on and the second switch is turned off, and obtaining a voltage applied to the other end of the first capacitor which is equivalent to a sum of the reference voltage and a difference between the upper end voltage and the lower end voltage in a state where the first and third switches are turned off and the second switch is turned on, wherein the circuit detects a voltage difference between the two ends of the current detection resistor based on a value obtained by the operational amplifier that subtracts the reference voltage from the obtained voltage.