Battery charger with low standby current
First Claim
1. An apparatus for charging a battery, comprising:
- a power supply terminal;
a controllable power control switch coupled to said power supply terminal;
a charging circuit coupled to said power control switch, said charging circuit having a charging terminal for connection to a terminal of the battery; and
control means, coupled to said power control switch, for detecting the presence of a battery connected to the charging terminal and for opening said power control switch if no battery is connected to the charging terminal.
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Accused Products
Abstract
An apparatus for charging a battery has a power supply terminal, a controllable power control switch coupled to said power supply terminal, a charging circuit having a charging terminal for connection to a terminal of the battery, and means for opening and closing the power control switch if a battery is disconnected or connected to the charging terminal, respectively. The means for opening and closing the power control switch may include an analog circuit, a digital circuit, a hybrid analog/digital circuit or a mechanical switch. A method of controlling a power control switch of a battery charging system is disclosed, comprising the steps of generating a reference voltage level, sensing the voltage level at the charging terminal, comparing the voltage level at the charging terminal to the reference voltage, and controlling the power control switch in response to the comparison of the reference voltage level and the voltage level at the charging terminal.
19 Citations
23 Claims
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1. An apparatus for charging a battery, comprising:
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a power supply terminal; a controllable power control switch coupled to said power supply terminal; a charging circuit coupled to said power control switch, said charging circuit having a charging terminal for connection to a terminal of the battery; and control means, coupled to said power control switch, for detecting the presence of a battery connected to the charging terminal and for opening said power control switch if no battery is connected to the charging terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of sensing the presence of a battery connected to a battery charging system having a charging terminal for connection to a terminal of the battery, comprising the steps of:
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generating a reference voltage level; sensing the voltage level at the charging terminal; and comparing the voltage level at the charging terminal to the reference voltage.
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16. A method of controlling a power control switch of a battery charging system having a charging terminal for connection to a terminal of the battery, comprising the steps of:
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generating a reference voltage level; sensing the voltage level at the charging terminal; comparing the voltage level at the charging terminal to the reference voltage; closing said power control switch if the reference voltage level exceeds the voltage level at the charging terminal; and opening said power control switch if the voltage level at the charging terminal exceeds the reference voltage level.
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17. A method of controlling a power control switch of a battery charging system having a charging terminal for connection to a terminal of the battery and an input terminal for connection to a voltage supply reference terminal of a battery powered device housing the battery, the method comprising the steps of:
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closing the power control switch; sensing the voltage level at the charging terminal; comparing the voltage level at the charging terminal to a first predetermined threshold value; and opening said power control switch if the voltage level at the charging terminal exceeds the first predetermined threshold value or if the voltage appearing at the input terminal is low. - View Dependent Claims (18)
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19. A method of controlling a power control switch of a battery charging system having a charging terminal for connection to a terminal of the battery and an input terminal for connection to a voltage supply reference terminal of a battery powered device housing the battery, the method comprising the steps of:
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opening the power control switch; sensing the voltage level at the charging terminal; comparing the voltage level at the charging terminal to a first predetermined threshold value; if the voltage level at the charging terminal does not exceed the first predetermined threshold value, comparing the voltage level at the charging terminal to a second predetermined threshold value; and if the voltage level at the charging terminal exceeds or is equal to the first predetermined threshold value, closing the power control switch. - View Dependent Claims (20, 21, 22, 23)
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Specification