Charging circuit
First Claim
1. A charging circuit which charges a battery based on a power supply voltage from an external power supply, the charging circuit comprising:
- a charging transistor which is provided on a charging path from the external power supply to the battery;
a charging control circuit which adjusts an ON state of the charging transistor to control a charging current supplied to the battery; and
a voltage adjusting circuit which is provided on an electric power supply path from the external power supply to a power supply terminal of the charging control circuit and generates a voltage drop, the voltage adjusting circuit, whereinthe charging control circuit comprises;
a clamp circuit which clamps a voltage at the power supply terminal of the charging control circuit below a predetermined clamp voltage; and
a current adjusting circuit which adjusts the ON state of the charging transistor such that a voltage of the battery is brought close to a predetermined voltage value.
1 Assignment
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Accused Products
Abstract
In a charging circuit charging a battery based on a power supply voltage from an external power supply, a charging transistor is provided on a path from the external power supply to the battery. A charging control circuit is integrated on a semiconductor substrate, and adjusts an ON state of the charging transistor to control a charging current supplied to the battery. The voltage adjusting circuit provided on an electric power supply path from the external power supply to a power supply terminal of the charging control circuit generates a necessary voltage drop. The current adjusting circuit adjusts the ON state of the charging transistor such that a voltage of the battery is brought close to a predetermined voltage value. The clamp circuit clamps a voltage at the power supply terminal of the charging control circuit below a predetermined clamp voltage.
14 Citations
22 Claims
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1. A charging circuit which charges a battery based on a power supply voltage from an external power supply, the charging circuit comprising:
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a charging transistor which is provided on a charging path from the external power supply to the battery; a charging control circuit which adjusts an ON state of the charging transistor to control a charging current supplied to the battery; and a voltage adjusting circuit which is provided on an electric power supply path from the external power supply to a power supply terminal of the charging control circuit and generates a voltage drop, the voltage adjusting circuit, wherein the charging control circuit comprises; a clamp circuit which clamps a voltage at the power supply terminal of the charging control circuit below a predetermined clamp voltage; and a current adjusting circuit which adjusts the ON state of the charging transistor such that a voltage of the battery is brought close to a predetermined voltage value. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An electronic equipment comprising:
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a battery; and a charging circuit comprising; a charging transistor which is provided on a charging path from the external power supply to the battery; a charging control circuit which adjusts an ON state of the charring transistor to control a charging current supplied to the battery; and a voltage adjusting circuit which is provided on an electric power supply path from the external power supply to a power supply terminal of the charging control circuit and generates a voltage drop, the voltage adjusting circuit, wherein the charging control circuit comprises; a clamp circuit which clamps a voltage at the power supply terminal of the charging control circuit below a predetermined clamp voltage; and a current adjusting circuit which adjusts the ON state of the charging transistor such that a voltage of the battery is brought close to a predetermined voltage value; wherein the charging circuit is structured to charge the battery based on a power supply voltage from an external power supply.
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9. An overvoltage protection circuit which is incorporated into a semiconductor integrated circuit, clamps a power supply voltage supplied to a power supply terminal of the semiconductor integrated circuit below a predetermined clamp voltage, the overvoltage protection circuit comprising:
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a first clamp circuit and a first switch which are provided in series between the power supply terminal and a fixed voltage terminal of the semiconductor integrated circuit; a reference voltage source which generates a predetermined reference voltage; and a comparator which compares the reference voltage with a voltage corresponding to the power supply voltage supplied to the power supply terminal, wherein the comparator turns on the first switch when the voltage corresponding to the power supply voltage is higher than the reference voltage. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A charging circuit which charges a battery based on a power supply voltage from an external power supply, the charging circuit comprising:
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a charging transistor which is provided on a path from the external power supply to the battery; a charging control circuit which is integrated on a semiconductor substrate, and adjusts an ON state of the charging transistor to control a charging current supplied to the battery; and a voltage adjusting circuit which is provided on an electric power supply path from the external power supply to a power supply terminal of the charging control circuit and generates a voltage drop, wherein the charging control circuit comprises; an overvoltage protection circuit that is structured to clamp a voltage at the power supply terminal of the charging control circuit below a predetermined clamp voltage, the overvoltage protection circuit comprising; a first clamp circuit and a first switch which are provided in series between the power supply terminal and a fixed voltage terminal of the semiconductor integrated circuit; a reference voltage source which generates a predetermined reference voltage; and a comparator which compares the reference voltage with a voltage corresponding to the power supply voltage supplied to the power supply terminal, wherein the comparator turns on the first switch when the voltage corresponding to the power supply voltage is higher than the reference voltage; and a current adjusting circuit which adjusts the ON state of the charging transistor such that a voltage of the battery is brought close to a predetermined voltage value. - View Dependent Claims (18, 19, 20, 21)
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22. An electronic equipment comprising:
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a battery; and a charging apparatus that is structured to charge the battery based on a power supply voltage from an external power supply, the charging apparatus comprising; a charging transistor which is provided on a path from the external power supply to the battery; a charging control circuit which is integrated on a semiconductor substrate, and adjusts an ON state of the charging transistor to control a charging current supplied to the battery; and a voltage adjusting circuit which is provided on an electric power supply path from the external power supply to a power supply terminal of the charging control circuit and generates a voltage drop, wherein the charging control circuit comprises; an overvoltage protection circuit that is structured to clamp a voltage at the power supply terminal of the charging control circuit below a predetermined clamp voltage, the overvoltage protection circuit comprising; a first clamp circuit and a first switch which are provided in series between the power supply terminal and a fixed voltage terminal of the semiconductor integrated circuit; a reference voltage source which generates a predetermined reference voltage; and a comparator which compares the reference voltage with a voltage corresponding to the power supply voltage supplied to the power supply terminal, wherein the comparator turns on the first switch when the voltage corresponding to the power supply voltage is higher than the reference voltage; and a current adjusting circuit which adjusts the ON state of the charging transistor such that a voltage of the battery is brought close to a predetermined voltage value.
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Specification