| 摘要 |
An apparatus for measuring current while applying a voltage, in which a predetermined voltage is applied to a noninverted input terminal of an operational amplifier, a voltage applied to a load is given to an inverted input terminal, a resistor for measuring current is connected between the output terminal of the operational amplifier and the load, and a voltage generated across the resistor for measuring current is measured to measure a current flowing into the load in a state where a predetermined voltage is applied to the load. A plurality of resistors for measuring currents is connected in series to meet a range for measuring current, a current by-pass switching element is connected in parallel with each of the resistors for measuring currents so as to be turned on when a voltage generated across the resistors for measuring currents has exceeded a predetermined voltage, voltages generating at the terminals of the resistors for measuring currents are automatically measured successively, the measured results are subjected to the subtraction to calculate voltages generated across the resistors for measuring currents, and an optimum value included in any one of the measuring ranges is selected from the calculated results to specify a current flowing into the load.
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