초록 ▼

A method and apparatus for protecting an energy-storage device (ESD), such as a rechargeable battery, is provided. A protective circuit protects an ESD from adverse charging and loading conditions including overcharging, overdischarging, charging at an excessive rate and discharging at an excessive

A method and apparatus for protecting an energy-storage device (ESD), such as a rechargeable battery, is provided. A protective circuit protects an ESD from adverse charging and loading conditions including overcharging, overdischarging, charging at an excessive rate and discharging at an excessive rate. The protective circuit selectively disables charging and discharging based on the present terminal conditions. A plurality of ESDs and protective circuits can be interconnected to protect a multi-cell ESD device. Embodiments of the protective circuit are adapted to protect a lithium cell operating around 2 volts. The protective circuit may also protect the ESD from adverse temperature conditions.

대표청구항 ▼

1. A protective circuit for an energy-storage device, comprising: a charge protection circuit adapted to disable current flow into the energy-storage device and allow current to flow out of the energy-storage device while a voltage corresponding to an overcharge state of the energy-storage device is

1. A protective circuit for an energy-storage device, comprising: a charge protection circuit adapted to disable current flow into the energy-storage device and allow current to flow out of the energy-storage device while a voltage corresponding to an overcharge state of the energy-storage device is detected;a discharge protection circuit adapted to disable current flow out of the energy-storage device when a voltage corresponding to an overdischarged state of the energy-storage device is detected until a voltage corresponding to an operating range of the energy-storage device is detected and allow current to flow into the energy-storage device while a voltage corresponding to the overdischarged state of the energy-storage device is detected;a first connection terminal configured for direct connection to an external load, a charger, and/or a second energy storage device;a second connection terminal configured for direct connection to the external load, the charger, and/or a third energy storage device; andan anti-parallel diode coupled between and directly connected to the first connection terminal and the second connection terminal. 2. The protective circuit of claim 1, wherein the discharge protection circuit comprises a p-channel FET. 3. The protective circuit of claim 2, wherein the p-channel FET is adapted and configured to selectively disable current flow out of the energy-storage device. 4. The protective circuit of claim 2, wherein the charge protection circuit comprises an n-channel FET adapted and configured to disable current flow into the energy-storage device. 5. The protective circuit of claim 1, wherein the discharge protection circuit comprises an n-channel FET and the charge protection circuit comprises an n-channel FET. 6. The protective circuit of claim 1, wherein the energy-storage device is a rechargeable battery. 7. The protective circuit of claim 6, wherein the operating range is between the lower bound voltage and an upper bound voltage, the lower bound voltage being 1.5 volts and the upper bound voltage being 2.5 volts. 8. The protective circuit of claim 6, wherein the voltage corresponding to the overcharged state is greater than an overcharged voltage of 2.65 volts and the overdischarged voltage is 1.40 volts. 9. The protective circuit of claim 1, in combination with a charging circuit and a rechargeable lithium battery cell wherein the protective circuit is electrically coupled between the rechargeable battery cell and the charging circuit. 10. The protective circuit of claim 1, wherein the first connection terminal is directly connected to the external load, the charger, and/or the second energy storage device. 11. The protective circuit of claim 10, wherein the second connection terminal is directly connected to the external load, the charger, and/or the third energy storage device. 12. An apparatus comprising a plurality of energy-storage devices and a plurality of protective circuits, each energy-storage device comprising a first terminal and a second terminal and each protective circuit having a first terminal and a second terminal coupled to the first terminal and the second terminal, respectively, of an energy-storage device of the plurality of energy-storage devices, each protective circuit comprising: a third terminal configured for direct connection to an external load, a charger, and/or a second energy storage device;a fourth terminal configured for direct connection to the external load, the charger, and/or a third energy storage device;an anti-parallel diode coupled between and directly connected to the third terminal and the fourth terminal;a first directional element coupled between the first terminal and the third terminal of the protective circuit adapted and configured to allow current flow in a first direction between the first terminal and the third terminal;a first switch coupled between the first terminal and the third terminal of the protective circuit in parallel with the first directional element, the first switch having a control input, the first switch being adapted and configured to selectively block current flow in response to a value in a first state at the control input of the first switch;an overdischarge detector having an input coupled between the third terminal and the fourth terminal of the protective circuit, the overdischarge detector having an output coupled to the control input of the first directional switch, the output of the overdischarge detector having a value in the first state when the voltage at the input of the overdischarge detector drops below a value corresponding to an overdischarge state and a value other than in the first state when the voltage at the input of the overdischarge detector raises to a voltage corresponding to an operating range;a second directional element coupled between the second terminal and the fourth terminal of the protective circuit, the second directional element being adapted and configured to allow current flow in a second direction between the second terminal and the fourth terminal;a second switch coupled between the second terminal and the fourth terminal of the protective circuit in parallel with the second directional element, the second switch having a control input, the second directional switch adapted and configured to block current flow between the second terminal and the fourth terminal in response to a value in a second state at the control input of the second switch; andan overcharge detector having an input coupled between the first terminal and the fourth terminal of the protective circuit, the overcharge detector having an output coupled to the control input of the second switch, the output of the overcharge detector having a value in the second state when the voltage at the input of the overcharge detector increases above a value corresponding to an overcharge state. 13. The apparatus of claim 12, wherein each protective circuit further comprises an over-temperature detector coupled to the control input of the first switch and the control input of the second switch, the over-temperature detector adapted and configured to provide a value in the first state to the control input of the first switch and a value in the second state to the control input of the second switch when the temperature is outside an acceptable range. 14. The apparatus of claim 12, wherein the first switch comprises a p-channel FET. 15. The apparatus of claim 14, wherein second switch comprises an n-channel FET. 16. The apparatus of claim 12, wherein the first switch comprises an n-channel FET. 17. The apparatus of claim 16, wherein second switch comprises a p-channel FET. 18. The apparatus of claim 12, wherein at least a portion of the plurality of protective circuits are connected in parallel. 19. The apparatus of claim 12, wherein at least a portion of the plurality of protective circuits are connected in series. 20. The apparatus of claim 12, wherein the plurality of energy-storage devices comprise lithium cells. 21. The apparatus of claim 12, further comprising a package; and wherein at least one of the plurality of energy-storage devices and at least one of the plurality of protective circuits is disposed within the package. 22. The apparatus of claim 12, wherein the third terminal is directly connected to the external load, the charger, and/or the second energy storage device. 23. The apparatus of claim 22, wherein the fourth terminal is directly connected to the external load, the charger, and/or the third energy storage device.