A battery pack may include at least one battery cell, a switch having an ON resistance dependent on a temperature of the switch, a thermistor having a resistance varying with changes in the temperature, and battery state monitoring circuitry. The battery state monitoring circuitry may be configured
A battery pack may include at least one battery cell, a switch having an ON resistance dependent on a temperature of the switch, a thermistor having a resistance varying with changes in the temperature, and battery state monitoring circuitry. The battery state monitoring circuitry may be configured to monitor a voltage drop across the switch caused by a current flowing through the switch and the resistance of the thermistor to correlate the voltage drop to the current level. A cordless electrical device including the battery pack, and an associated method are also provided.
대표청구항▼
1. An apparatus comprising: a battery pack comprising: at least one battery cell;a first and a second voltage terminal coupled to said at least one battery cell, said first and said second voltage terminals configured to be removably coupled to a load;a switch disposed between said at least one batt
1. An apparatus comprising: a battery pack comprising: at least one battery cell;a first and a second voltage terminal coupled to said at least one battery cell, said first and said second voltage terminals configured to be removably coupled to a load;a switch disposed between said at least one battery cell and at least one of said first and said second voltage terminals, said switch having an ON resistance dependent on a temperature of said switch;a thermistor located proximate said switch, said thermistor having a resistance varying with changes in said temperature, wherein said thermistor is configured to sense said temperature of said switch and to output a signal representative of said temperature of said switch; andbattery state monitoring circuitry configured to determine a current flowing to or from said at least one battery cell based on a voltage drop across said switch caused by a current flowing through said switch and said signal from said thermistor representative of said temperature of said switch. 2. The apparatus of claim 1, wherein said switch comprises a discharge switch configured to close to enable said at least one battery cell to provide a discharge current to said load, said voltage drop representative of said discharge current. 3. The apparatus of claim 2, wherein said discharge switch comprises a metal oxide semiconductor field effect transistor (MOSFET) and said voltage drop is a voltage drop across a drain and source terminal of said MOSFET. 4. The apparatus of claim 3, wherein said battery state monitoring circuitry comprises a sense amplifier having one input coupled to said drain of said MOSFET and another input coupled to said source of said MOSFET, said sense amplifier configured to amplify said voltage drop across said drain and source terminal of said MOSFET and provide an output signal representative of said current flowing through said switch. 5. The apparatus of claim 1, wherein said switch comprises a charge switch configured to close to enable said at least one battery cell to be charged with a charge current from a charging source, said voltage drop representative of said charge current. 6. A cordless electrical device comprising: a load; anda battery pack to provide power to said load, said battery pack comprising: a first and a second voltage terminal configured to be removably coupled to said load;at least one battery cell configured to be coupled to said first and said second voltage terminals;a switch disposed between said at least one battery cell and at least one of said first and said second voltage terminals, said switch having an ON resistance dependent on a temperature of said switch;a thermistor having a resistance varying with changes in said temperature, wherein said thermistor is configured to sense said temperature of said switch and to output a signal representative of said temperature of said switch; andbattery state monitoring circuitry configured to determine a current flowing to or from said at least one battery cell based on a voltage drop across said switch caused by a current flowing through said switch and said signal from said thermistor representative of said temperature of said switch. 7. The cordless electrical device of claim 6, wherein said thermistor is located proximate said switch. 8. The cordless electrical device of claim 6, wherein said switch comprises a discharge switch configured to close to enable said at least one battery cell to provide a discharge current to a load, said voltage drop representative of said discharge current. 9. The cordless electrical device of claim 8, wherein said discharge switch comprises a metal oxide semiconductor field effect transistor (MOSFET) and said voltage drop is a voltage drop across a drain and source terminal of said MOSFET. 10. The cordless electrical device of claim 9, wherein said battery state monitoring circuitry comprises a sense amplifier having one input coupled to said drain of said MOSFET and another input coupled to said source of said MOSFET, said sense amplifier configured to amplify said voltage drop across said drain and source terminal of said MOSFET and provide an output signal representative of said current flowing through said switch. 11. The cordless electrical device of claim 6, wherein said switch comprises a charge switch configured to close to enable said at least one battery cell to be charged with a charge current from a charging source, said voltage drop representative of said charge current. 12. A method comprising: monitoring a voltage drop across a switch disposed between at least one battery cell and at least one of a first and a second voltage terminal of a battery pack when said switch is closed, said switch having an ON resistance dependent on a temperature of said switch;sensing a temperature of said switch comprising monitoring a resistance of a thermistor as a function of temperature, said resistance of said thermistor representative of said temperature of said switch; anddetermining a current flowing to or from said battery pack based on a voltage drop across said switch caused by a current flowing through said switch and said signal from said thermistor representative of said temperature of said switch. 13. The method of claim 12, wherein said current is further determined based on an initial gain of said switch. 14. The method of claim 12, wherein said switch comprises a discharge switch and said current comprises a discharge current flowing from said at least one battery cell of said battery pack to a load, said discharge switch comprising a metal oxide semiconductor field effect transistor (MOSFET) and said voltage drop being a voltage drop across a drain and source terminal of said MOSFET.
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이 특허에 인용된 특허 (14)
Becker-Irvin Craig H., Battery cell voltage monitor and method.
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