Method and apparatus for measuring battery depletion in implantable medical devices
First Claim
1. An apparatus for measuring battery depletion in an implantable medical device comprising:
- a capacitor disposed in series connection between the battery and a load;
means for switching polarity of said capacitor; and
means for generating an indication of depletion of the battery based on a number of times said capacitor switches polarity.
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Abstract
A method and apparatus for measuring battery depletion in an implantable medical device is presented. The apparatus includes first and second switch pairs disposed in series between the battery and a load, and connected in a parallel arrangement with respect to one another. A capacitor is connected in a first polarity between the battery and the load when only first and fourth switches are closed and in a second polarity when only second and third switches are closed. A comparator circuit causes the switches to reverse the capacitor'"'"'s polarity based on a comparison of the voltage drop across the capacitor to a threshold value. A counter counts the number of times the capacitor reverses polarity, which is proportional to the amount of charge transferred from the battery during its lifetime in the device and indicative of the battery'"'"'s level of depletion.
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Citations
20 Claims
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1. An apparatus for measuring battery depletion in an implantable medical device comprising:
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a capacitor disposed in series connection between the battery and a load; means for switching polarity of said capacitor; and means for generating an indication of depletion of the battery based on a number of times said capacitor switches polarity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus for measuring current supplied by a battery to a load, comprising:
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a first switch pair having first and second switches connected to one another at a first node, said first switch pair being disposed in series between the battery and the load; a second switch pair having third and fourth switches connected to one another at a second node, said second switch pair being disposed in series between the battery and the load, wherein said first and second switch pairs are connected in a parallel arrangement with respect to one another; a capacitor connected between said first and second nodes such that said capacitor is connected in a first polarity between the battery and the load when only said first and fourth switches are closed, and said capacitor is connected in a second polarity between the battery and the load when only said second and third switches are closed; a comparator circuit to cause said switches to reverse polarity of said capacitor based on a comparison of a voltage across said capacitor to a threshold value; and a counter to count a number of times that said capacitor reverses polarity, said count being indicative of current drawn from the battery. - View Dependent Claims (13, 14, 15)
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16. A method for measuring battery depletion in an implantable medical device, comprising:
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monitoring a voltage across a capacitor serially connected between the battery and a load; comparing said voltage to a threshold value; switching polarity of said capacitor when said voltage exceeds said threshold value; and counting a number of times said capacitor switches polarity, wherein said number of times is proportional to an amount of charge transferred from said battery over time. - View Dependent Claims (17, 18, 19, 20)
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Specification