Battery Management for an Implantable Medical Device

• US 20130023943A1
• Filed: 06/06/2012
• Published: 01/24/2013
• Est. Priority Date: 07/20/2011
• Status: Active Grant

• Current Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Inventors: Parramon, Jordi, Marnfeldt, Goran N., Ozawa, Robert, Feldman, Emanuel, Peterson, Dave
• Granted Patent: US 9,393,433 B2
• Time in Patent Office: Days
• US Class Current: 607/2
• CPC Class Codes: A61N 1/3787 from an external energy source

Abstract

Battery management circuitry for an implantable medical device such as an implantable neurostimulator is described. The circuitry has a T-shape with respect to the battery terminal, with charging circuitry coupled between rectifier circuitry and the battery terminal on one side of the T, and load isolation circuitry coupled between the load and the battery terminal on the other side. The load isolation circuitry can comprise two switches wired in parallel. An undervoltage fault condition opens both switches to isolate the battery terminal from the load to prevent further dissipation of the battery. Other fault conditions will open only one the switches leaving the other closed to allow for reduced power to the load to continue implant operations albeit at safer low-power levels. The battery management circuitry can be fixed in a particular location on an integrated circuit which also includes for example the stimulation circuitry for the electrodes.

Claims

1. Circuitry for an implantable medical device, comprising:

a first charging path comprising a source for receiving an input voltage and for producing power to charge a battery;

a second charging path for receiving the input voltage, wherein the second charging path couples to the battery terminal node by at least one first one diode; and

at least one load switch coupled between the battery terminal node and a load within the implantable medical device, wherein the at least one load switch is opened at least if an undervoltage signal is received.

2. The circuitry of claim 1, wherein the circuitry is integrated on an integrated circuit.

3. The circuitry of claim 1, wherein the power producible by the source is a constant current, or a constant voltage, or both.

4. The circuitry of claim 1, wherein there are first and second load switches coupled in parallel between the battery terminal node and the load.

5. The circuitry of claim 4, wherein the first load switch is opened if the undervoltage signal is received, and wherein the second load switch is opened if either the undervoltage signal is received or an overcurrent signal is received.

6. The circuitry of claim 5, further comprising an overcurrent detector for asserting the overcurrent signal if a current through the at least one load switch exceeds a threshold.

7. The circuit of claim 5, wherein the resistance of the first load switch is larger than the resistance of the second load switch.

8. The circuitry of claim 5, wherein the second load switch is additionally opened if a magnetic field detected signal is received.

9. The circuitry of claim 1, further comprising at least one second diode between the first and second charging paths.

10. The circuitry of claim 1, wherein the first charging path further comprises an overvoltage switch for gating the produced power to a battery terminal node, wherein the overvoltage switch is opened if an overvoltage signal is received.

11. The circuitry of claim 10, wherein the at least one first diode and the at least one second diode are connected at their positive terminal, and wherein their negative terminals are coupled to either side of the overvoltage switch.

12. The circuitry of claim 11, wherein the number of first diodes and the number of second diodes are the same.

13. The circuitry of claim 1, wherein the second charging path is passive.

14. The circuitry of claim 1, further comprising a coil and rectifier circuit for producing the input voltage.

15. The circuitry of claim 14, further comprising a diode between the rectifier circuit and the input voltage.

16. The circuitry of claim 1, further comprising an undervoltage detector for receiving the battery terminal node and for asserting the undervoltage signal when the voltage at the battery terminal node falls below a threshold.

17. The circuitry of claim 1, wherein the undervoltage detector is passive and doesn'"'"'t require any control signals to assert the undervoltage signal.

18. The circuitry of claim 1, further comprising a discharge circuit for receiving the battery terminal node, wherein the discharge circuitry couples the battery terminal node to ground when an overvoltage signal is received, but wherein the discharge circuitry decouples the battery terminal node from ground when an undervoltage signal is received.

19. Circuitry for an implantable medical device, comprising:

charging circuitry for providing power to a battery terminal node; and

isolation circuitry comprising first and second load switches coupled in parallel between the battery terminal node and the load.

20. The circuitry of claim 19, wherein the first load switch has a first resistance, and the second load switch has a second resistance smaller than the first resistance.

21. The circuitry of claim 19,

wherein the first load switch is opened if the voltage at the battery terminal node falls below a threshold, and

wherein the second load switch is opened if either the voltage at the battery terminal node falls below a threshold or if at least one other fault condition is asserted.

22. The circuitry of claim 21, wherein the first load switch has a first resistance, and the second load switch has a second resistance smaller than the first resistance.

23. The circuitry of claim 21, wherein the fault condition comprises an overcurrent between the battery terminal node and the load.

24. The circuitry of claim 21, wherein the fault conditions comprise an overcurrent between the battery terminal node and the load and an emergency shutdown condition.

25. The circuitry of claim 24, wherein the emergency shutdown condition comprises a magnetic field generated external to the implantable medical device.

26. Circuitry useable in an implantable medical device comprising:

an integrated circuit, comprising;

stimulation circuitry for stimulating a plurality of electrodes coupleable to outputs on the integrated circuit;

a battery input/output from the integrated circuit coupleable to a battery terminal;

battery management circuitry for (i) receiving an input voltage for charging the battery, and (ii) producing a power supply voltage from the battery; and

a load powered by the power supply voltage, wherein the load comprises the stimulation circuitry.

27. The circuitry of claim 26, wherein the load further comprises other circuitry on the integrated circuit.

28. The circuitry of claim 27, wherein the load further comprises circuitry coupleable to an load output of the integrated circuit.

29. The circuitry of claim 28, wherein the circuitry coupleable to the load output comprises a microcontroller.

30. The circuitry of claim 26, wherein the input voltage is supplied to an input of the integrated circuit and is used for producing power to charge the battery.

31. The circuitry of claim 30, wherein the input is coupleable to rectifier circuitry for producing the input voltage.

32. The circuitry of claim 26, wherein the battery management circuitry is isolated from other circuitry on the integrated circuit.

33. The circuitry of claim 32, wherein the battery management circuitry is isolated by a ring of insulation around the battery management circuitry.

34. The circuitry of claim 26, further comprising bus inputs/outputs coupleable to a bus outside of the integrated circuitry.

35. The circuitry of claim 34, wherein the bus inputs/outputs couples to a source controller for providing at least one control signal to a power source in the battery management circuitry for producing the power for charging the battery.

36. The circuitry of claim 35, wherein the at least one control signal is AC coupled to the power source.