System and method for measuring battery current
First Claim
1. A battery-powered medical device, comprising:
- circuitry to be powered by and draw current from a battery to provide medical therapy;
a current measurement circuit to measure the current drawn from the battery; and
means to calibrate the current measuring circuit when the current measurement circuit is measuring the current drawn from the battery.
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Abstract
Systems, devices and methods are provided for measuring battery current. According to one aspect, a medical device is provided that comprises a battery, a pulse generator, and a current measuring device. The pulse generator draws a pulse generator current from the power source, and the current measuring device determines the pulse generator current or tracks charge depletion from the battery. The current measuring device comprises an oscillator and a counter. The oscillator produces an oscillating output with a frequency of oscillation dependent on the pulse generator current, and the counter provides an oscillation count for the oscillating output. The current measuring device is capable of being calibrated while continuously determining the pulse generator current. In one embodiment, the current measuring device includes at least two current sources, each including an operational amplifier that has an autozeroing feature.
115 Citations
20 Claims
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1. A battery-powered medical device, comprising:
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circuitry to be powered by and draw current from a battery to provide medical therapy;
a current measurement circuit to measure the current drawn from the battery; and
means to calibrate the current measuring circuit when the current measurement circuit is measuring the current drawn from the battery. - View Dependent Claims (2, 3)
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4. A medical device, comprising:
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a battery terminal for connection to a battery;
a pulse generator connected to the battery terminal to draw a pulse generator current and generate electrical therapy pulses; and
a current measuring device to determine the pulse generator current and to be calibrated while determining the pulse generator current. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12)
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13. A device for determining a pulse generator current drawn from a battery of an implantable medical device, comprising:
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a first means to provide a first input current dependent on the pulse generator current;
a second means to provide a second input current dependent on the pulse generator current;
means to receive the first and second input current and provide an output with a frequency of oscillation dependent on the pulse generator current; and
means to count the frequency of oscillation of the output. - View Dependent Claims (14)
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15. A device for determining a pulse generator current drawn from a battery of an implantable medical device, comprising:
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a current source to provide an input current dependent on the pulse generator current, wherein the current source is adapted to be calibrated while providing the input current;
an oscillator to receive the input current and produce an oscillating output, wherein the oscillating output has a frequency of oscillation dependent on the pulse generator current; and
a counter to provide an oscillation count for the oscillating output, wherein the pulse generator current is determined from the oscillation count. - View Dependent Claims (16, 17, 18)
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19. A method to measure current in a battery-operated medical device, comprising:
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selecting one of a first current source and a second current source to provide an input current to charge an oscillator, wherein the input current is dependent on a current drawn from a battery;
calibrating the second current source when the first current source provides the input current to charge the oscillator;
counting a number of oscillations resulting from the input current provided by the first current source;
calibrating the first current source when the second current source provides the input current to charge the oscillator; and
counting a number of oscillations resulting from the input current provided by the second current source. - View Dependent Claims (20)
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Specification