Multiple battery charger with a power source control
First Claim
1. A battery charging apparatus which continuously. charges multiple batteries during a charging cycle, comprising:
- a power supply which provides charging current to all batteries simultaneously;
a plurality of linear current limiters coupled to said power supply and each linear current limiter further connected to a respective battery to continuously provide charging current to said respective battery during said charging cycle, wherein each current limiter includes means to control the amount of charging current supplied to said respective battery; and
means, coupled to said power supply and to each battery, and to each of said plurality of linear current limiters, for providing feedback information indicative of a voltage level of said respective battery to each of said plurality of current limiters, wherein each of said plurality of linear current limiters reduces the voltage drop across itself in response to said feedback information to maintain substantially constant current through said respective battery during said charging cycle.
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Abstract
A battery charging system is disclosed that includes an efficient switch mode power supply, multiple linear current limiters, and feedback means to allow the switch mode power supply to operate at the minimum voltage necessary to operate a power load and charge batteries. Furthermore, the switch mode power supply is capable of producing the maximum power required by the system, such as when the battery charger is used in conjunction with operation of a electronic device with peak load demands such as when a hard disk is accessed in a portable computer. Two control mechanisms are found in the battery charging system. The first mechanism is an input used to control the switch mode power supply output voltage from an external source. In one embodiment, this is done by referencing a first voltage to that internal to the switch mode power supply. The second mechanism is to limit the current within the switch mode power supply not controlled by an external source. This current limiting feature is linear and is set at an absolute limit point. Each limiter supplies charge current to a battery, which charge current is monitored and compared to a reference voltage with the resulting error voltage used to control the output of a series pass controller, such as a transistor.
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Citations
8 Claims
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1. A battery charging apparatus which continuously. charges multiple batteries during a charging cycle, comprising:
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a power supply which provides charging current to all batteries simultaneously; a plurality of linear current limiters coupled to said power supply and each linear current limiter further connected to a respective battery to continuously provide charging current to said respective battery during said charging cycle, wherein each current limiter includes means to control the amount of charging current supplied to said respective battery; and means, coupled to said power supply and to each battery, and to each of said plurality of linear current limiters, for providing feedback information indicative of a voltage level of said respective battery to each of said plurality of current limiters, wherein each of said plurality of linear current limiters reduces the voltage drop across itself in response to said feedback information to maintain substantially constant current through said respective battery during said charging cycle. - View Dependent Claims (2, 3)
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4. A battery charging apparatus which continuously charges at least first and second batteries during a charging cycle, said apparatus comprising:
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a power supply which provides charging current to said first and second batteries simultaneously; and at least first and second current limiters, wherein each current limiter is connected between said power supply and a respective one of said at least first and second batteries to continuously supply charging current to said battery connected thereto during said charging cycle, and wherein each current limiter senses a voltage proportional to an actual current level through said battery connected thereto, each current limiter comparing said sensed voltage with a reference voltage to obtain a feedback signal used to adjust the voltage drop across itself so as to maintain substantially constant charging current through said battery connected thereto. - View Dependent Claims (5, 6)
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7. A battery charger which continuously charges a plurality of batteries during a charging cycle comprising:
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a power supply which provides a voltage output to all batteries simultaneously; a plurality of current control circuits, wherein each current control circuit is connected between said power supply and a respective one of said batteries to continuously supply charging current to said respective battery during said charging cycle, each of said current control circuits sensing a voltage proportional to an actual current level through said respective battery and comparing said sensed voltage with a reference voltage to obtain a feedback signal indicative of the voltage level of said respective battery; and a feedback circuit which receives said feedback signals from said current control circuits and generates a voltage control output signal based upon a lowest level feedback signal, wherein said power supply receives said voltage control output signal and adjusts the voltage output therefrom to a level required to charge the battery with the greatest voltage level. - View Dependent Claims (8)
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Specification