초록 ▼

The present invention relates to a battery protection circuit for protecting a plurality of batteries connected in series. The battery protection circuit includes: a controller for monitoring the batteries and outputting control signals based on predetermined conditions associated with the batteries

The present invention relates to a battery protection circuit for protecting a plurality of batteries connected in series. The battery protection circuit includes: a controller for monitoring the batteries and outputting control signals based on predetermined conditions associated with the batteries; a first N-channel MOSFET and a second N-channel MOSFET coupled in a common-drain configuration in a low-side path, wherein at least one of the first and second N-channel MOSFETs turns off in response to the control signal received from the controller when at least one of the predetermined conditions is detected; and a gate protection circuit for preventing gate-to-source voltages of the first and second N-channel MOSFETs from exceeding a predetermined gate-to-source voltage level.

대표청구항 ▼

What is claimed is: 1. A battery protection circuit for protecting a plurality of batteries connected in series by controlling: (1) a discharging current flowing from the batteries through a load detachably attached between a positive terminal and a negative terminal, or (2) a charging current flow

What is claimed is: 1. A battery protection circuit for protecting a plurality of batteries connected in series by controlling: (1) a discharging current flowing from the batteries through a load detachably attached between a positive terminal and a negative terminal, or (2) a charging current flowing to the batteries from a charger detachably attached between the positive terminal and the negative terminal, the battery protection circuit comprising: a controller for monitoring the batteries and outputting control signals based on predetermined conditions associated with the batteries; a first N-channel MOSFET and a second N-channel MOSFET coupled in a common-drain configuration in a low-side path, wherein at least one of the first and second N-channel MOSFETs turns off in response to the control signal received from the controller when at least one of the predetermined conditions is detected; and a gate protection circuit for preventing gate-to-source voltages of the first and second N-channel MOSFETs from exceeding a predetermined voltage level; wherein the gate protection circuit comprises: a small-signal FET having a drain coupled to a gate of the second N-channel MOSFET and a source coupled to the negative terminal, wherein the small-signal FET turns on and clamps the gate-to-source voltage of the second N-channel MOSFET when the gate-to-source voltage of the second N-channel MOSFET increases to a predetermined gate-to-source voltage level during a period when the second N-channel MOSFET is off and the charger is attached. 2. The battery protection circuit according to claim 1, wherein: the first N-channel MOSFET turns off the discharging current in response to the control signal when the load is attached; and the second N-channel MOSFET turns off the charging current in response to the control signal when the charger is attached. 3. The battery protection circuit according to claim 1, wherein the gate protection circuit further comprises: a first diode having an anode coupled to the source of the small-signal FET and a cathode coupled to a gate of the small-signal FET; and a first resistor having one end coupled to the cathode of the first diode and the other end coupled to a ground, wherein current that flows through the first diode and the first resistor controls ON/OFF of the small-signal FET. 4. The battery protection circuit according to claim 1, wherein the gate protection circuit further comprises: a second diode having an anode coupled to an output pin of the controller and a cathode coupled to the gate of the second N-channel MOSFET and the drain of the small-signal FET for reducing leakage current flowing into the output pin. 5. The battery protection circuit according to claim 1, wherein the gate protection circuit further comprises: a second resistor coupled to an output pin of the controller and to a gate of the first N-channel MOSFET for providing a voltage drop to the gate of the first N-channel MOSFET; and a third resistor coupled to the output pin of the controller and the gate of the second N-channel MOSFET for providing a voltage drop to the gate of the second N-channel MOSFET. 6. The battery protection circuit according to claim 2, wherein the controller comprises: an over-discharge detection circuit for detecting an over-discharge condition as the predetermined condition, the over-discharge detection circuit monitoring at least one cell voltage and processing information on the over-discharge condition when at least one cell voltage falls below a predetermined over-discharge detection voltage. 7. The battery protection circuit according to claim 6, wherein the over-discharge detection circuit further detects an over-discharge cancellation and processes information on the over-discharge cancellation for turning on the first N-channel MOSFET when the at least one cell voltage exceeds a predetermined over-discharge cancellation voltage. 8. The battery protection circuit according to claim 2, wherein the controller comprises: an over-charge detection circuit for detecting an over-charge condition as the predetermined condition, the over-charge detection circuit monitoring at least one cell voltage and processing information on the over-charge condition when at least one cell voltage exceeds a predetermined over-charge detection voltage. 9. The battery protection circuit according to claim 8, wherein the over-charge detection circuit further detects an over-charge cancellation and processes information on the over-charge cancellation for turning on the second N-channel MOSFET when the at least one cell voltage falls below a predetermined over-charge cancellation voltage. 10. The battery protection circuit according to claim 2, wherein the controller comprises: an over-current detection circuit for detecting an over-current condition as the predetermined condition, the over-current detection circuit monitoring the charging or discharging current and processing information on the over-current condition when the charging or discharging current exceeds a predetermined over-current value. 11. The battery protection circuit according to claim 10, wherein the over-current detection circuit further detects an over-current cancellation and processes information on the over-current cancellation for turning on the first N-channel MOSFET for the discharging current when the discharging current falls below the predetermined over-current value, or turning on the second N-channel MOSFET for the charging current when the charging current falls below the predetermined over-current value. 12. The battery protection circuit according to claim 2, further comprising at least one temperature sensing device for measuring at least one battery temperature, respectively, wherein the controller comprises: an over-temperature detection circuit for detecting an over-temperature condition as the predetermined condition based on measurements by the at least one temperature sensing device, the over-temperature detection circuit processing information on the over-temperature condition when at least one battery temperature exceeds a predetermined temperature value. 13. The battery protection circuit according to claim 12, wherein the over-temperature detection circuit further detects an over-temperature cancellation and processes information on the over-temperature cancellation for turning on the first N-channel MOSFET for the discharging current or the second N-channel MOSFET for the charging current when the at least one battery temperature falls below the predetermined temperature value. 14. The battery protection circuit according to claim 1, wherein at least part of the gate protection circuit is integrated with the controller on a same chip. 15. The battery protection circuit according to claim 1, wherein at least part of the gate protection circuit is integrated with the first and second N-channel MOSFETs on a same chip. 16. The battery protection circuit according to claim 1, wherein at least part of the gate protection circuit and the first and second N-channel MOSFETs are integrated with the controller on a same chip. 17. The battery protection circuit according to claim 1, the battery is a Lithium Sulfur battery. 18. A battery protection circuit comprising: a positive terminal and a negative terminal configured to be coupled to a plurality of batteries in series, the plurality of batteries having a total voltage of 7.5 volts or greater, wherein a discharging current flows from the batteries through a load detachably attached between the positive terminal and the negative terminal, or a charging current flows to the batteries from a charger detachably attached between the positive terminal and the negative terminal; a controller for monitoring the batteries and outputting control signals based on predetermined conditions associated with the batteries; a first N-channel MOSFET and a second N-channel MOSFET coupled in a common-drain configuration in a low-side path, wherein the first N-channel MOSFET turns off the discharging current in response to the control signal, and the second N-channel MOSFET turns off the charging current in response to the control signal; and a small-signal FET that turns on and clamps a gate-to-source voltage of the second N-channel MOSFET when the gate-to-source voltage of the second N-channel MOSFET increases to a predetermined level. 19. The battery protection circuit according to claim 18, further comprising: a first diode having an anode coupled to a source of the small-signal FET and a cathode coupled to a gate of the small-signal FET, wherein a drain of the small-signal FET is coupled to a gate of the second N-channel MOSFET and the source of the small-signal FET is further coupled to the negative terminal; a first resistor having one end coupled to the cathode of the first diode and the other end coupled to a ground, wherein current that flows through the first diode and the first resistor controls ON/OFF of the small-signal FET; a second diode having an anode coupled to an output pin of the controller and a cathode coupled to the gate of the second N-channel MOSFET and the drain of the small-signal FET for reducing leakage current flowing into the output pin; a second resistor coupled to the output pin of the controller and to a gate of the first N-channel MOSFET for providing a first voltage drop to the gate of the first N-channel MOSFET; and a third resistor coupled to the output pin of the controller and the gate of the second N-channel MOSFET for providing a second voltage drop to the gate of the second N-channel MOSFET. 20. The battery protection circuit according to claim 18, wherein the controller comprises: an over-discharge detection circuit for detecting an over-discharge condition as one of the predetermined conditions, the over-discharge detection circuit monitoring at least one cell voltage and processing information on the over-discharge condition when at least one cell voltage exceeds a predetermined over-discharge detection voltage; and an over-charge detection circuit for detecting an over-charge condition as another of the predetermined conditions, the over-charge detection circuit monitoring at least one cell voltage and processing information on the over-charge condition when at least one cell voltage exceeds a predetermined over-charge detection voltage. 21. The battery protection circuit according to claim 18, wherein the controller comprises: an over-current detection circuit for detecting an over-current condition as the predetermined condition, the over-current detection circuit monitoring the charging or discharging current and processing information on the over-current condition when the charging or discharging current exceeds a predetermined over-current value. 22. The battery protection circuit according to claim 18, further comprising at least one temperature sensing device for measuring at least one battery temperature, respectively, wherein the controller comprises: an over-temperature detection circuit for detecting an over-temperature condition as the predetermined condition based on measurements by the at least one temperature sensing device, the over-temperature detection circuit processing information on the over-temperature condition when at least one battery temperature exceeds a predetermined temperature value. 23. The battery protection circuit according to claim 18, the battery is a Lithium Sulfur battery. 24. A battery protection circuit comprising: a positive terminal and a negative terminal configured to be coupled to three or more batteries in series, wherein a discharging current flows from the batteries through a load detachably attached between the positive terminal and the negative terminal, or a charging current flows to the batteries from a charger detachably attached between the positive terminal and the negative terminal; a controller for monitoring the batteries and outputting control signals based on predetermined conditions associated with the batteries; a first N-channel MOSFET and a second N-channel MOSFET coupled in a common-drain configuration in a low-side path, wherein the first N-channel MOSFET turns off the discharging current in response to the control signal, and the second N-channel MOSFET turns off the charging current in response to the control signal; and a small-signal FET that turns on and clamps a gate-to-source voltage of the second N-channel MOSFET when the gate-to-source voltage of the second N-channel MOSFET increases to a predetermined level.