Charging circuit with battery charge monitor circuit
First Claim
1. A charging circuit comprising:
- a constant current source for supplying a constant current for charging a battery;
a comparator having one input terminal, the other input terminal supplied with a reference potential and an output terminal connected to said one input terminal for generating an output signal having a period dependent upon a voltage of said battery;
a capacitor connected between said one input terminal of said comparator and a ground potential;
a resistor inserted between an output terminal of said constant current source and said one input terminal of said comparator; and
a temperature compensating element connected in series with said resistor between said output terminal of said constant current source and said one input terminal of said comparator for compensating for a variation of period of the output signal caused by temperature dependent change of capacitance of said capacitor.
1 Assignment
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Accused Products
Abstract
A charging circuit charges a nickel-cadmium battery by means of a constant current source. A resistor, diodes and a tantalum capacitor are connected between an output terminal of the charging circuit and a ground potential. A junction between the capacitor and the diode is connected to one input terminal and an output terminal of a comparator and to the output terminal of the charging circuit. The other input terminal of the comparator is supplied with a reference potential. An output signal having a period which depends on a voltage of the battery is generated at the output terminal. The diodes compensate for a variation of the period of the output signal caused by temperature dependent capacitance change of the capacitor.
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Citations
6 Claims
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1. A charging circuit comprising:
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a constant current source for supplying a constant current for charging a battery; a comparator having one input terminal, the other input terminal supplied with a reference potential and an output terminal connected to said one input terminal for generating an output signal having a period dependent upon a voltage of said battery; a capacitor connected between said one input terminal of said comparator and a ground potential; a resistor inserted between an output terminal of said constant current source and said one input terminal of said comparator; and a temperature compensating element connected in series with said resistor between said output terminal of said constant current source and said one input terminal of said comparator for compensating for a variation of period of the output signal caused by temperature dependent change of capacitance of said capacitor. - View Dependent Claims (2, 3, 4)
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5. A battery charge monitor circuit comprising:
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a comparator having one input terminal, the other input terminal supplied with a reference potential and an output terminal connected to said one input terminal for generating an output signal having a period dependent upon a voltage of a battery which is charged; a capacitor connected between said one input terminal of said comparator and a ground potential; a resistor inserted between an output terminal of a constant current source and said one input terminal of said comparator; a temperature compensating element connected in series with said resistor between said output terminal of said constant current source and said one input terminal of said comparator for compensating for a variation of period of the output signal caused by temperature dependent change of capacitance of said capacitor; and monitor means for monitoring the output of said comparator. - View Dependent Claims (6)
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Specification