Remaining capacity detection circuit of rechargeable battery, electronic apparatus using the same, automobile, and detecting method for state of charge

A remaining capacity detection circuit for detecting SOC (State Of Charge) of a rechargeable battery, comprising:

• a coulomb counter circuit for generating a coulomb count value CC by integrating charge and discharge currents of the battery;
• a voltage detection circuit for detecting a battery voltage VBAT of the battery;
• an SOC calculator for calculating an SOC value SOC1 by Equation (1):
• SOC1=(CCFULL−CC)/CCFULL×100 (1),
• wherein CCFULL is a coulomb count capacity value corresponding to full charge;
• and
• a correction circuit, performing:
• a step of generating an OCV (Open Circuit Voltage) value OCV1 corresponding to the value SOC1 on the basis of an SOC-OCV characteristic indicating a relation between SOC and OCV predetermined for the battery;
• a step of generating a voltage drop VDROP1 between the value OCV1 and a voltage value VBAT1 detected by the voltage detection circuit;
• a step of generating a value OCV2 which is higher than a minimum operating voltage VBAT_MIN of the system by a voltage width ΔV corresponding to the voltage drop VDROP1;
• a step of generating an SOC value SOC2 corresponding to the value OCV2 based on the SOC-OCV characteristic;
• and
• a step of generating a correction result by correcting at least one of the values SOC1, CC, CCFULL, and SOC-OCV characteristic on the assumption that the value SOC2 corresponds to zero remaining capacity, wherein the battery is charged or discharged using the correction result generated by the correction circuit.