CLOCK SYNCHRONIZATION IN AN IMPLANTABLE MEDICAL DEVICE SYSTEM

• US 20110190850A1
• Filed: 01/29/2010
• Published: 08/04/2011
• Est. Priority Date: 01/29/2010
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Terry, Michael B., Patil, Kaustubh R., Corey, Robert A., Roberts, Jonathan P., Reinke, James D., Ecker, Robert M.
• Granted Patent: US 8,396,563 B2
• Time in Patent Office: Days
• US Class Current: 607/60
• CPC Class Codes: A61N 1/37288 Communication to several implantable medical devices within one patient
• CPC Class Codes: G06F 1/06 Clock generators producing several clock signals G06F1/08 - G06F1/14 take precedence
• CPC Class Codes: G06F 1/12 Synchronisation of different clock signals provided by a plurality of clock generators

Abstract

This disclosure is directed to the synchronization of clocks of a secondary implantable medical device (IMD) to a clock of a primary IMD. The secondary IMD includes a communications clock. The communications clock may be synchronized based on at least one received communications pulse. The secondary IMD further includes a general purpose clock different than the communications clock. The general purpose clock may be synchronized based on at least one received power pulse. The communications clock may also be synchronized based on the at least one received power pulse.

Claims

1. A method comprising:

receiving, from a primary implantable medical device (IMD), by a secondary IMD communicatively coupled to the primary IMD, at least one data pulse;

receiving, from the primary IMD by the secondary IMD, at least one power pulse;

synchronizing, by the secondary IMD, a first clock local to the secondary IMD using the at least one data pulse; and

synchronizing, by the secondary IMD, a second clock local to the secondary IMD using the at least one power pulse, wherein the second clock is different than the first clock.

2. The method of claim 1, wherein synchronizing, by the secondary IMD, the second clock local to the secondary IMD using the at least one power pulse include synchronizing the second clock local to the secondary IMD to a clock local to the primary IMD.

3. The method of claim 2, wherein synchronizing the second clock with a clock local to the primary IMD includes synchronizing to a crystal clock of the primary IMD.

4. The method of claim 1, wherein synchronizing, by the secondary IMD, a first clock local to the secondary IMD includes synchronizing a communications clock of the secondary IMD.

5. The method of claim 1, wherein synchronizing the first clock local to the secondary IMD using the at least one data pulse includes synchronizing an intermittent clock of the secondary IMD, wherein the intermittent clock is configured to turn off when the secondary IMD is not operating to communicate.

6. The method of claim 1, wherein synchronizing the second clock local to the secondary IMD includes synchronizing a general purpose clock of the secondary IMD.

7. The method of claim 1, wherein the at least one power pulse comprises a first power pulse, and further comprising:

estimating, based on the second clock, an arrival time of a subsequent power pulse; and

detecting, via at least one sensor of the secondary IMD, at least one condition based on an estimated arrival time of the subsequent power pulse.

8. The method of claim 7, wherein detecting, via the at least one sensor of the secondary IMD, at least one condition includes turning off at least one detection operation of at least one sensor during arrival of the subsequent power pulse based on the estimated arrival time.

9. The method of claim 1, further comprising:

synchronizing the first clock local to the secondary IMD using the at least one power pulse.

10. The method of claim 1, further comprising:

using the second clock to perform at least one operation of the secondary IMD, the at least one operation selected from the group consisting of;

defining a time period for at least one sensor of the secondary IMD to detect one or more patient conditions;

identifying a duration of a power-on reset signal for the secondary IMD;

accessing information stored in one or more memories of the secondary IMD; and

calibrating sensor elements of the secondary IMD.

11. A system comprising:

at least one primary implantable medical device (IMD) configured to operate based on a local clock;

at least one secondary IMD communicatively coupled to the primary IMD and configured to receive at least one communication pulse and at least one power pulse from the primary IMD;

a communications clock unit configured to generate a first clock of the secondary IMD based on the at least one communication pulse; and

a general purpose clock unit configured to generate a second clock different than the first clock based on the at least one power pulse.

12. The system of claim 11, wherein the communications clock unit is configured to generate the second clock by synchronizing the second clock to the local clock of the primary IMD.

13. The system of claim 12, wherein the local clock of the primary IMD is based on a crystal oscillator.

14. The system of claim 11, wherein the first clock of the secondary IMD is an intermittent clock configured to turn off when the secondary IMD is not operating to communicate.

15. The system of claim 11, wherein the at least one power pulse comprises a first power pulse, and wherein the secondary IMD is further operable to:

estimate, based on the first power pulse, an estimated arrival time of a subsequent power pulse; and

detect, via at least one sensor of the secondary IMD, at least one condition based on an estimated arrival time of the subsequent power pulse.

16. The system of claim 11, wherein at least one sensor of the secondary IMD is operable to detect the at least one condition by turning off at least one detection operation during arrival of the subsequent power pulse based on the estimated arrival time.

17. The system of claim 11, wherein the communications clock unit is further operable to:

turn off the first clock when a communications pulse has not been detected for a predetermined amount of time.

18. The system of claim 11, wherein the communications clock unit is further operable to:

synchronize the first clock local to the sensor based on the at least one power pulse.

19. The system of claim 11, wherein the secondary IMD is configured to use the second clock to perform at least one operation of the secondary IMD, the at least one operation selected from the group consisting of:

define a time period for at least one sensor of the secondary IMD to detect one or more patient conditions;

identify a duration of a power-on reset signal for the secondary IMD;

access information stored in one or more memories of the secondary IMD; and

calibrate sensor elements of the secondary IMD.

20. A device, comprising:

means for receiving at least one communications pulse for communicating a message;

means for receiving at least one power pulse for powering the device;

means for generating a first clock based on the at least one communications pulse; and

means for generating a second clock different than the first clock based on the at least one power pulse.

21. The device of claim 20, wherein the first clock is a communications clock.

22. The device of claim 20, wherein the means for generating the first clock turn off the first clock when the device is not operating to communicate.

23. The device of claim 20, wherein the means for generating a second clock generate a general purpose clock.

24. The device of claim 20, wherein the at least one power pulse comprises a first power pulse, and further comprising:

means for estimating, based on the second clock, an estimated arrival time of a subsequent power pulse; and

means for detecting at least one condition based on the estimated arrival time of the subsequent power pulse.

25. The device of claim 24, further comprising:

means for turning off at least one detection operation of at least one sensor during arrival of the subsequent power pulse based on the estimated arrival time.

26. The device of claim 20, wherein the device is configured to use the second clock to perform at least one operation of the device, the at least one operation selected from the group consisting of:

define a time period for at least one sensor of the device to detect one or more patient conditions;

identify a duration of a power-on reset signal for the device;

access information stored in one or more memories of the device; and

calibrate sensor elements of the device.

27. The device of claim 20, further comprising:

means for turning off the first clock when at least one data pulse has not been received for a predetermined amount of time.

28. The device of claim 20, wherein the means for generating the first clock also generate the first clock based on the at least one power pulse.

29. A device comprising:

a communications unit configured to receive, from a primary implantable medical device (IMD), at least one data pulse and at least one power pulse;

a communications clock unit configured to synchronize a first clock local to the device based at least in part on the at least one data pulse; and

a general purpose clock unit configured to synchronize a second clock local to the device different than the first clock based at least in part on the at least one power pulse.

30. The device of claim 29, wherein the general purpose clock unit is configured to synchronize the second clock to a clock local to the primary IMD by synchronizing the second clock based at least in part on the at least one power pulse.

31. The device of claim 30, wherein the clock local to the primary IMD is a crystal clock of the primary IMD.

32. The device of claim 29, wherein the first clock is an intermittent clock of the device configured to turn off the first clock when the secondary IMD is not operating to communicate.

33. The device of claim 29, wherein the at least one power pulse comprises a first power pulse, and wherein the device is further configured to estimate, based on the second clock, an arrival time of a subsequent power pulse;

and

detect, via at least one sensor of the device, at least one condition based on the estimated arrival time of the subsequent power pulse.

34. The device of claim 33, wherein the device is configured to detect the at least one condition based on the estimated arrival time of the subsequent power pulse by turning off at least one detection operation of at least one sensor during arrival of the subsequent power pulse based on the estimated arrival time.

35. The device of claim 29, wherein the communications clock unit is further configured to synchronize the first clock based at least in part on the at least one power pulse.

36. The device of claim 29, wherein the device is configured to use the second clock to perform at least one operation of the device, the at least one operation selected from the group consisting of:

define a time period for at least one sensor of the device to detect one or more patient conditions;

identify a duration of a power-on reset signal for the device;

access information stored in one or more memories of the device; and

calibrate sensor elements of the device.