Small highly accurate battery temperature monitoring circuit
First Claim
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1. A battery temperature measuring circuit operable with a battery and a temperature sensing device, comprising:
- the temperature monitoring device connected to the battery and configured to output a measured voltage representative of battery temperature;
a first comparator circuit that generates a first output signal, the first comparator circuit comparing the measured voltage to a first reference voltage when the first output signal has a safe logic state, and changing the safe logic state of the first output signal to an unsafe logic state when the measured voltage exceeds the first reference voltage;
a second comparator circuit that generates a second output signal, the second comparator circuit comparing the measured voltage to a second reference voltage when the second output signal has a safe logic state, and changing the safe logic state of the second output signal to an unsafe logic state when the measured voltage falls below the second reference voltage; and
a current source circuit connected to the temperature sensing device, and the first comparator circuit and the second comparator circuit, the current source circuit sourcing a first constant current to the first comparator circuit when the measured voltage rises above an upper voltage, and a second constant current to the second comparator circuit when the measured voltage falls below a lower voltage, the upper voltage being less than the first reference voltage and greater than the second reference voltage, the lower voltage being less than the upper voltage and greater than the second reference voltage.
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Abstract
A battery temperature monitoring circuit, which has a cold comparator and a hot comparator, achieves high accuracy in a small cell size by utilizing a cold current optimized for the cold comparator and a cold reference voltage, and a hot current optimized for the hot comparator and a hot reference voltage, along with switching circuitry that provides the cold current to the cold comparator as the battery temperature approaches the cold trip temperature, and the hot current to the hot comparator as the battery temperature approaches the hot trip temperature.
21 Citations
20 Claims
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1. A battery temperature measuring circuit operable with a battery and a temperature sensing device, comprising:
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the temperature monitoring device connected to the battery and configured to output a measured voltage representative of battery temperature; a first comparator circuit that generates a first output signal, the first comparator circuit comparing the measured voltage to a first reference voltage when the first output signal has a safe logic state, and changing the safe logic state of the first output signal to an unsafe logic state when the measured voltage exceeds the first reference voltage; a second comparator circuit that generates a second output signal, the second comparator circuit comparing the measured voltage to a second reference voltage when the second output signal has a safe logic state, and changing the safe logic state of the second output signal to an unsafe logic state when the measured voltage falls below the second reference voltage; and a current source circuit connected to the temperature sensing device, and the first comparator circuit and the second comparator circuit, the current source circuit sourcing a first constant current to the first comparator circuit when the measured voltage rises above an upper voltage, and a second constant current to the second comparator circuit when the measured voltage falls below a lower voltage, the upper voltage being less than the first reference voltage and greater than the second reference voltage, the lower voltage being less than the upper voltage and greater than the second reference voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of measuring battery temperature employable with a battery and a temperature monitoring device comprising:
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generating from the temperature monitoring device a measured voltage representative of battery temperature; generating, from a first comparator circuit, a first output signal based on comparing the measured voltage to a first reference voltage when the first output signal has a safe logic state, and changing the safe logic state of the first output signal to an unsafe logic state when the measured voltage exceeds the first reference voltage; generating, from a second comparator circuit, a second output signal based on comparing the measured voltage to a second reference voltage when the second output signal has a safe logic state, and changing the safe logic state of the second output signal to an unsafe logic state when the measured voltage falls below the second reference voltage; and selectively providing to the first and second comparators, respectively first and second constant currents, including sourcing the first constant current to the first comparator circuit when the measured voltage exceeds an upper voltage; and sourcing the second constant current to the second comparator circuit when the measured voltage falls below a lower voltage, the upper voltage being less than the first reference voltage and greater than the second reference voltage, and the lower voltage being less than the upper voltage and greater than the second reference voltage. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A battery system including temperature monitoring, comprising:
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a temperature monitoring device connected to the battery and configured to output a measured voltage representative of battery temperature; a battery temperature monitoring circuit, including a first comparator circuit that generates a first output signal, the first comparator circuit comparing the measured voltage to a first reference voltage when the first output signal has a safe logic state, and changing the safe logic state of the first output signal to an unsafe logic state when the measured voltage exceeds the first reference voltage; a second comparator circuit that generates a second output signal, the second comparator circuit comparing the measured voltage to a second reference voltage when the second output signal has a safe logic state, and changing the safe logic state of the second output signal to an unsafe logic state when the measured voltage falls below the second reference voltage; and a current source circuit connected to the temperature sensing device, and the first comparator circuit and the second comparator circuit, the current source circuit sourcing a first constant current to the first comparator circuit when the measured voltage rises above an upper voltage, and a second constant current to the second comparator circuit when the measured voltage falls below a lower voltage, the upper voltage being less than the first reference voltage and greater than the second reference voltage, the lower voltage being less than the upper voltage and greater than the second reference voltage. - View Dependent Claims (17, 18, 19, 20)
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Specification