Voltage adapter circuit for a lithium ion rechargeable battery
First Claim
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1. A voltage adjustment circuit for a Li-ion rechargeable battery comprising:
- means for determining by a first comparison circuit whether the rechargeable battery is in a charging state, a discharging state or a stand-by state, and the first comparison circuit turns on or off a first switching element accordingly;
means for comparing by a second comparison circuit, during the battery is in a discharging state, the voltages between an input voltage and a reference voltage, and the second comparison circuit turns on or off a second switching element accordingly;
the first compassion circuit coupling to the second comparison circuit, wherein said first switching element is connected with said second switching element in parallel to create two possible passages for the input/output current;
means for protecting the battery by a protection circuit from over-charge/discharge of the battery due to any excess load current or any large short circuit current, where the protection circuit controls a third and a forth switching elements accordingly, and said third switching element is connected with said forth switching element in series, where either said third switching element or said forth switching element will be able to turn off the current passage;
a first pair of bi-directional terminals (P+, P−
) are used by both charging(input) operation and discharging(output) operation; and
a second pair of terminals (C+, C−
) are used to connect the Li-ion rechargeable battery.
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Abstract
The present invention is a circuit that uses only one pair of bi-directional terminals for both charging and discharging a rechargeable battery. When the circuit detects that the battery is in the charging process, it opens an unrestricted current passage and lets the rechargeable battery fully charge. When the circuit detects the battery is in discharging process, if needed, it will induce a voltage drop of 0.7v and reduce the Li-Ion rechargeable battery'"'"'s output voltage from 4.2v to desired voltage range 3.3˜3.6v. In addition, the circuit provides a feature that prevents the battery from over-charging or over-discharging.
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11 Claims
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1. A voltage adjustment circuit for a Li-ion rechargeable battery comprising:
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means for determining by a first comparison circuit whether the rechargeable battery is in a charging state, a discharging state or a stand-by state, and the first comparison circuit turns on or off a first switching element accordingly;
means for comparing by a second comparison circuit, during the battery is in a discharging state, the voltages between an input voltage and a reference voltage, and the second comparison circuit turns on or off a second switching element accordingly;
the first compassion circuit coupling to the second comparison circuit, wherein said first switching element is connected with said second switching element in parallel to create two possible passages for the input/output current;
means for protecting the battery by a protection circuit from over-charge/discharge of the battery due to any excess load current or any large short circuit current, where the protection circuit controls a third and a forth switching elements accordingly, and said third switching element is connected with said forth switching element in series, where either said third switching element or said forth switching element will be able to turn off the current passage;
a first pair of bi-directional terminals (P+, P−
) are used by both charging(input) operation and discharging(output) operation; and
a second pair of terminals (C+, C−
) are used to connect the Li-ion rechargeable battery. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification