| 摘要 |
PROBLEM TO BE SOLVED: To provide a current sensing circuit having a simple configuration, which is capable of accurately sensing current without being influenced by temperature characteristics of a shunt resistor.SOLUTION: A current sensing circuit includes: an integrator circuit comprising an operational amplifier with an input resistor whose temperature coefficient is same as that of a shunt resistor which converts current being measured into voltage and a capacitor on a feedback part; a comparator with hysteresis characteristics, which compares output voltage from the integrator circuit with first and second threshold values and sets the output signal thereof either to High or Low; a charge switch which allows voltage across the shunt resistor to be fed to the operational amplifier via the input resistor to charge the capacitor when the comparator output signal is High; a discharge switch which allows electrical charge accumulated in the capacitor to be discharged via a discharge resistor when the comparator output signal is Low; and a counter which counts the time during which the comparator output signal is High. |
