System for managing power to an implanted device based on operating time, current drain and battery capacity

• US 6,664,763 B2
• Filed: 03/12/2001
• Issued: 12/16/2003
• Est. Priority Date: 04/26/1999
• Status: Expired due to Fees

• Current Assignee: Exonix Corporation
• Original Assignee: Exonix Corporation
• Inventors: Jimenez, Oscar, Echarri, Roberto, Echarri, Guillermo, Barreras, Francisco Jose Sr.
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/803,189
• Publication Number:
  US 20020140399A1
• Time in Patent Office: 1,009 Days
• Field of Search: 320/106, 320/107, 320/108, 320/110, 320/114, 320/127, 320/130, 320/132, 320/134, 320/135, 320/136, 320/149, 320/155, 320/160, 320/162, 320/163
• US Class Current: 320/132
• CPC Class Codes: A61N 1/3708 for power depletion
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/0029 with safety or protection devices or circuits
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/007194 of the battery

Abstract

The method and system manage power supplied from a charging circuit to a power source in an implantable medical device utilizing measurements of current drain; measurements of elapsed time since the last full charge; calculations of operating time based on the variable of current drain and the variable of the actual capacity of the power source; sensing of voltage level above a certain value; and monitoring of the temperature of the power source during charging and discharging.

Claims

1. In a method for operating an implantable medical device having a rechargeable power source with a changing capacity and being implanted in a patient, the improvement comprising the steps of:

charging the power source inductively from a charging circuit of a power management system located outside the patient and without a hard wire connection to the power source from the charging circuit;

updating, on the power management system, a reading of the capacity of the power source, after each charge/discharge cycle and indicating to the patient with the power management system when the power source needs to be recharged.

2. The method of claim 1 including the steps of:

monitoring, during charging of the power source of the implanted device, the incoming charge supplied inductively to the power source of the implanted device;

supplying a constant current source to the power source up to a predetermined high voltage; and

, upon the battery voltage reaching said predetermined high value, topping-off the charge on the power source by switching to a constant voltage until the charging current diminishes to a predetermined low value.

3. The method of claim 1 including the steps of:

monitoring the temperature of the power source during charging of the power source of the implanted device and interrupting charging if the temperature exceeds a predetermined high value and until the temperature drops below a set value.

4. The method of claim 1 including the steps of:

monitoring when the power source of the implanted device reaches a fully charged state, and, with circuitry in the implanted device, turning off the flow of current into the power source of the implanted device, even if the external charging unit would continue to transmit electromagnetic waves to the implanted device.

5. The method of claim 1 including the steps of:

measuring, during discharging, with circuitry in the implanted device, the current drain of the power source in the implanted device and the elapsed time until a predetermined low voltage level is reached; and

transmitting these values non-invasively to the external power management system.

6. The method of claim 1 including the steps of:

calculating with the power management system the “

faded”

capacity for the next recharge cycle and, based on this “

faded”

capacity and current drain, displaying on the power management system the estimated “

total”

operating time left for the implanted device.

7. The method of claim 1 including the steps of:

calculating, with circuitry in the implanted device, the “

faded”

capacity and “

total”

operating time left and transmitting this information to the power management system.

8. The method of claim 1 including the steps of:

monitoring, during the discharge cycle, the battery voltage on the power source in the implanted device and upon reaching a predetermined value, disconnecting the power source from the implanted device to prevent deep discharging of the power source which would greatly reduce the available number of recharge cycles.

9. In a method for managing power supplied inductively from a charging circuit of a power management system located outside of a patient to a power source in an implantable medical device implanted in the patient, the improvement comprising the steps of:

measuring with circuitry in the implanted device and then non-invasively transmitting from the implanted device to the external power management system (1) the current drain of the implanted power source and (2) the elapsed time since the last full charge to discharge of the implanted power source to a pre-determined low voltage, and then calculating (3) the faded capacity in ampere-hours by multiplying the current drain (1) times the elapsed time (2), and finally to calculate the operating time of the implanted device by dividing the faded capacity (3) by the current drain (1), and then displaying on the power management system, the calculated operating time left.

10. The method of claim 9 including the steps of:

monitoring, during charging of the power source of the implanted device, the incoming charge supplied inductively to the power source of the implanted device;

supplying a constant current source to the power source up to a predetermined high voltage; and

, upon the battery voltage reaching said predetermined high value, topping-off the charge on the power source by switching to a constant voltage until the current diminishes to a predetermined low value.

11. The method of claim 9 including the steps of:

monitoring the temperature of the power source during charging of the power source of the implanted device and interrupting charging if the temperature exceeds a predetermined high value and until the temperature drops below a set value.

12. The method of claim 9 including the steps of:

monitoring when the power source of the implanted device reaches a fully charged state, and, with circuitry in the implanted device, turning off the flow of current into the power source of the implanted device, even if the external charging unit would continue to transmit electromagnetic waves to the implanted device.

13. In a system for operating an implantable medical device having a rechargeable power source with a changing capacity and being implanted in a patient, the improvement comprising:

means for charging the power source inductively from outside the patient and without a hard wire connection to the power source;

means for updating a reading of the capacity of the power source by a power management system located outside of the patient, after each charge/discharge cycle and means for indicating to the patient with the power management system when the power source needs to be recharged.

14. The system of claim 13 including means for monitoring, during charging of the power source of the implanted device, the incoming charge supplied inductively to the power source of the implanted device;

means for supplying a constant current source to the power source up to a predetermined high voltage; and

means for topping-off the charge on the power source, upon the battery voltage reaching said predetermined high value, by switching to a constant voltage until the charging current diminishes to a predetermined low value.

15. The system of claim 13 including means for monitoring the temperature of the power source during charging of the power source of the implanted device and means for interrupting charging if the temperature exceeds a predetermined high value and until the temperature drops below a set value.

16. The system of claim 13 including means for monitoring when the power source of the implanted device reaches a fully charged state, and circuitry in the implanted device for turning off the flow of current into the power source of the implanted device, even if the external charging unit would continue to transmit electromagnetic waves to the implanted device.

17. The system of claim 13 including circuit means in the implanted device for measuring, during discharging, the current drain of the power source in the implanted device and the elapsed time until a predetermined low voltage level is reached;

and means for transmitting these values non-invasively to the external power management system.

18. The system of claim 13 including means in the power management system for calculating the “

faded”

capacity for the next recharge cycle and means for displaying on the power management system, the estimated “

total”

operating time left for the implanted device based on the “

faded”

capacity and current drain.

19. The system of claim 13 including means in the implanted device for calculating the “

faded”

capacity and “

total”

operating time left and means for transmitting this information to the power management system.

20. The system of claim 13 including means in the implanted device for monitoring, during the discharge cycle, the battery voltage on the power source in the implanted device and means for disconnecting the power source from the implanted device upon reaching a predetermined low voltage to prevent deep discharging of the power source which would greatly reduce the available number of recharge cycles.

21. In a system for managing power supplied inductively from a charging circuit of a power management system located outside of a patient to a power source in an implantable medical device implanted in the patient, the improvement comprising means for measuring with circuitry in the implanted device and then non-invasively transmitting from the implanted device to the external power management system (1) the current drain of the implanted power source and (2) the elapsed time since the last full charge to discharge of the implanted power source to a pre-determined low voltage, and means for calculating (3) the faded capacity in ampere-hours by multiplying the current drain (1) times the elapsed time (2), and means for calculating the operating time of the implanted device by dividing the faded capacity (3) by the current drain (1), and means for displaying on the power management system, the calculated operating time left.

22. The system of claim 21 including means for monitoring, during charging of the power source of the implanted device, the incoming charge supplied inductively to the power source of the implanted device;

means for supplying a constant current source to the power source up to a predetermined high voltage; and

means for topping-off the charge on the power source, upon the battery voltage reaching said predetermined high value, by switching to a constant voltage until the charging current diminishes to a predetermined low value.

23. The system of claim 21 including means for monitoring the temperature of the power source during charging of the power source of the implanted device and means for interrupting charging if the temperature exceeds a predetermined high value and until the temperature drops below a set value.

24. The system of claim 21 including means for monitoring when the power source of the implanted device reaches a fully charged state, and circuitry in the implanted device for turning off the flow of current into the power source of the implanted device, even if the external charging unit would continue to transmit electromagnetic waves to the implanted device.