Meter for measuring battery charge delivered in an implantable device
First Claim
1. A battery charge meter for use in monitoring the amount of charge delivered by a battery in an implantable device comprising:
- a sensor coupled to the battery, for providing a sense signal corresponding to the electrical current being drawn from the battery;
a voltage-controlled oscillator circuit that generates a VCO signal having a frequency that corresponds to the sense signal; and
a counter that counts the cycles of the VCO signal to produce a measurement of depleted battery charge.
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Accused Products
Abstract
An improved apparatus and method are described for providing a measurement of the charge depleted from a battery used in an implantable device such as a cardiac pacemaker. The measurement is provided not by measuring the voltage level or impedance of the battery, but rather by continuously measuring the electrical current drawn from the battery and integrating that measured current over an integration time period. A precision current-sensing resistor provides a sense signal having a voltage that varies according to the magnitude of current being drawn, and this sense signal is integrated using a voltage-controlled oscillator circuit and counter, which are implemented using CMOS circuitry arranged in a switched-capacitor topology.
132 Citations
18 Claims
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1. A battery charge meter for use in monitoring the amount of charge delivered by a battery in an implantable device comprising:
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a sensor coupled to the battery, for providing a sense signal corresponding to the electrical current being drawn from the battery; a voltage-controlled oscillator circuit that generates a VCO signal having a frequency that corresponds to the sense signal; and a counter that counts the cycles of the VCO signal to produce a measurement of depleted battery charge. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An implantable biomedical device, comprising:
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a biomedical circuit configured to monitor one or more parameters of a living body; a battery for supplying a time-varying electrical current to the biomedical circuit; and a battery charge delivery meter, including a sensor coupled to the battery, said sensor providing a sense signal corresponding to electrical current being drawn from the battery, and an integrator coupled to the sensor for integrating the sense signal to produce a measurement of the depleted battery charge over an integration time period. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A battery charge delivery meter for a battery supplying an electrical current to a load circuit, comprising:
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sensor means coupled to the battery, for providing a sense signal corresponding to the electrical current being drawn from the battery; oscillator means for generating a sequence of signal pulses, wherein each signal pulse has a duration representing a predetermined discrete quantity of charge depleted from the battery; and counter means for counting the signal pulses generated by the oscillator means, to produce the measurement of depleted battery charge. - View Dependent Claims (17)
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18. A method for determining the charge in a battery that supplies a time-varying electrical current to a load circuit, comprising:
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sensing the electrical current being drawn from the battery to provide a sense signal; generating a sequence of signal pulses, wherein each signal pulse has a duration representing a predetermined discrete quantity of charge depleted from the battery; and counting the signal pulses to produce a measurement of depleted battery charge.
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Specification