Remaining battery capacity measuring device
First Claim
1. A remaining battery capacity measuring device comprising:
- a current measuring circuit for measuring charging and discharging currents of a secondary battery, said current measuring circuit including;
a differential amplifier circuit for detecting a voltage across a resistor for current detection connected in series with the secondary battery,an offset voltage regulator circuit for selectively applying an offset voltage to the differential amplifier circuit and for variably setting the offset voltage, anda gain adjusting circuit for variably setting a gain of the differential amplifier circuit.
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Accused Products
Abstract
A remaining battery capacity measuring device having a microprocessor and an integrated circuit is packaged together with a secondary battery to form a battery pack. The integrated circuit includes a current measuring circuit for charging and discharging currents of a secondary battery, an overcurrent detection circuit for detecting overcurrent in the secondary battery, a driver circuit for driving a semiconductor switch for change and discharge control of the secondary battery, and a power switch circuit for power-saving operation. The current measuring circuit includes an operational amplifier for detecting a voltage across a resistor for current detection, and has a function to apply a variable offset voltage to the amplifier and a function to vary the gain of another operational amplifier for amplifying the output of the former operational amplifier. The current measuring circuit detects the voltage across the resistor independently of the overcurrent detection circuit, and enjoys high measurement accuracy. The overcurrent detection level and overcurrent detection response time of the overcurrent detection circuit can be externally set by an external divider circuit and an external variable capacitor. The power switch circuit selectively connects various circuit sections of the battery capacity measuring device to a power source, depending on the operating state, charging or discharging, of the secondary battery.
46 Citations
47 Claims
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1. A remaining battery capacity measuring device comprising:
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a current measuring circuit for measuring charging and discharging currents of a secondary battery, said current measuring circuit including; a differential amplifier circuit for detecting a voltage across a resistor for current detection connected in series with the secondary battery, an offset voltage regulator circuit for selectively applying an offset voltage to the differential amplifier circuit and for variably setting the offset voltage, and a gain adjusting circuit for variably setting a gain of the differential amplifier circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A remaining battery capacity measuring device, comprising:
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a current measuring circuit for detecting a voltage across a resistor for current detection connected in series with a secondary battery and for measuring charging and discharging currents of the secondary battery in accordance with the voltage across the resistor; and an overcurrent detection circuit for detecting the voltage across the resistor independently of said current measuring circuit and for detecting overcurrent in the secondary battery in accordance with the detected voltage across the resistor. - View Dependent Claims (21, 22, 23, 24, 25)
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26. A remaining battery capacity measuring device, comprising:
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an overcurrent detection circuit for detecting overcurrent in a secondary battery, said overcurrent detection circuit including; a differential amplifier for detecting a voltage across a resistor for current detection connected in series with the secondary battery; a comparator for comparing an externally set reference value with an output of the differential amplifier and for outputting an output signal indicative of the generation of overcurrent when the reference value is exceeded by the output of the differential amplifier; and a timer circuit for starting time measurement in response to an output signal of the comparator and for outputting an overcurrent detection signal when an externally set time is over. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A remaining battery capacity measuring device, comprising:
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a current detection circuit including first and second differential amplifiers each connected to opposite ends of a resistor for current detection, connected in series with a secondary battery, so as to input the voltage across the resistor in polarity different between the first and second differential amplifiers, each of the first and second differential amplifiers detecting an electric current flowing through the secondary battery based on the voltage across the resistor; and a power switch circuit for selectively connecting the first or second differential amplifier to a power source, depending on the direction of the electric current flowing through the secondary battery. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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Specification