Voltage switching circuit, secondary battery protection circuit, and battery pack
First Claim
1. A voltage switching circuit for a secondary battery protection circuit installed in a battery pack having a negative power supply terminal and a current-detection resistor,the voltage switching circuit comprising:
- a first input terminal to which a voltage obtained by converting a current flowing through the current-detection resistor of the battery pack to voltage is supplied;
a second input terminal to which a voltage at the negative power supply terminal of the battery pack and a voltage at a charger negative power supply terminal of the secondary battery protection circuit are supplied;
an output terminal to output an output voltage to a detection circuit in the secondary battery protection circuit; and
a selection terminal to select either the voltage from the first input terminal or the voltage from the second input terminal as the output voltage for output through the output terminal,wherein the voltage switching circuit causes the output voltage to switch between the voltage from the first input terminal and the voltage from the second input terminal in accordance with selection of the selection terminal either when an excess current is detected with the battery pack in a chargeable-dischargeable state or when the battery pack returns to the chargeable-dischargeable state from a charge-discharge inhibit state.
2 Assignments
0 Petitions
Accused Products
Abstract
A voltage switching circuit for a secondary battery protection circuit in a battery pack having a negative power supply terminal and a current-detection resistor. The secondary battery protection circuit has a charger negative power supply terminal and a detection circuit. The voltage switching circuit has a first input terminal to which a voltage obtained by converting a current flowing through the current detection resistor is supplied, a second input terminal to which voltages at the negative power supply terminal and at the charger negative power supply terminal are supplied, an output terminal, and a selection terminal. The voltage switching circuit causes an output voltage to switch between the voltages from the first input terminal and the second input terminal according to selection at the selection terminal when an excess current is detected and when the battery pack returns to a chargeable-dischargeable state from a charge-discharge inhibit state.
13 Citations
20 Claims
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1. A voltage switching circuit for a secondary battery protection circuit installed in a battery pack having a negative power supply terminal and a current-detection resistor,
the voltage switching circuit comprising: -
a first input terminal to which a voltage obtained by converting a current flowing through the current-detection resistor of the battery pack to voltage is supplied; a second input terminal to which a voltage at the negative power supply terminal of the battery pack and a voltage at a charger negative power supply terminal of the secondary battery protection circuit are supplied; an output terminal to output an output voltage to a detection circuit in the secondary battery protection circuit; and a selection terminal to select either the voltage from the first input terminal or the voltage from the second input terminal as the output voltage for output through the output terminal, wherein the voltage switching circuit causes the output voltage to switch between the voltage from the first input terminal and the voltage from the second input terminal in accordance with selection of the selection terminal either when an excess current is detected with the battery pack in a chargeable-dischargeable state or when the battery pack returns to the chargeable-dischargeable state from a charge-discharge inhibit state. - View Dependent Claims (2, 3, 4, 5)
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6. A secondary battery protection circuit installed in a battery pack having a negative power supply terminal, a current-detection resistor, and a switching element connected in series to the current-detection resistor, the battery pack connected to a secondary battery and one of a charger and a load,
the secondary battery protection circuit comprising: -
a sensing terminal, connected between the current-detection resistor and the switching element, to which a voltage obtained by converting a current flowing through the current-detection resistor to voltage is supplied; a charger negative power supply terminal connected to the negative power supply terminal of the battery pack; a voltage switching circuit to cause an output voltage to switch, the voltage switching circuit comprising; a first input terminal to which the voltage at the sensing terminal is supplied; a second input terminal to which a voltage at the negative power supply terminal of the battery pack and a voltage at the charger negative power supply terminal of the secondary battery protection circuit are supplied; an output terminal to output the output voltage; and a selection terminal to select either the voltage from the first input terminal or the voltage from the second input terminal for output through the output terminal as the output voltage; and a detection circuit to detect an excess current and output a detection result to the selection terminal of the voltage switching circuit to switch off the switching element and shut off the current flowing through the switching element and the current-detection resistor when the excess current is detected. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A battery pack to charge and discharge a secondary battery, connectable to one of a charger and a load,
the battery pack comprising: -
a negative power supply terminal connected to one of negative terminals of the charger and the load; a switching element to connect and disconnect the secondary battery and one of the charger and the load; a current-detection resistor to detect a charging current and a discharging current, connected in series to the switching element; and a secondary battery protection circuit to protect the secondary battery from an excess current, the secondary battery protection circuit comprising; a sensing terminal connected between the current-detection resistor and the switching element, to which a voltage obtained by converting a current flowing through the current-detection resistor to voltage is supplied; a charger negative power supply terminal, connected to the negative power supply terminal of the battery pack, to which a voltage at the negative power supply terminal of the battery pack is supplied; a detection circuit to detect the excess current; and a voltage switching circuit, having a first input terminal to which the voltage at the sensing terminal is supplied, a second input terminal to which a voltage at the negative power supply terminal of the battery pack and a voltage at the charger negative power supply terminal of the secondary battery protection circuit are supplied, an output terminal to output an output voltage to the detection circuit, and a selection terminal to which an output signal from the detection circuit is supplied and to select either the voltage from the first input terminal or the voltage from the second input terminal for output through the output terminal as the output voltage, wherein the voltage switching circuit switches between the voltage from the first input terminal and the voltage from the second input terminal for output as the output voltage when either excess current is detected while the battery pack is in a chargeable-dischargeable state or the battery pack returns to the chargeable-dischargeable state from a charge-discharge inhibit state. - View Dependent Claims (18, 19, 20)
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Specification