Implantable medical devices and systems having power management for recharge sessions

• US 9,042,995 B2
• Filed: 02/03/2010
• Issued: 05/26/2015
• Est. Priority Date: 02/03/2010
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Dinsmoor, David A., Anderson, Joel A., Denison, Timothy
• Primary Examiner(s): Heller, Tammie K
• Application Number:
  US12/699,830
• Publication Number:
  US 20110190853A1
• Time in Patent Office: 1,938 Days
• Field of Search: 607/60, 607/61
• US Class Current: 607/60
• CPC Class Codes: A61N 1/378 Electrical supply
• CPC Class Codes: A61N 1/3787 from an external energy source

Abstract

Implantable devices and related systems utilize power management features in conjunction with a recharge circuit that includes a coil and capacitance. The reactance such as the capacitance and/or inductance may be variable such that in the event of an overcharge condition, the reactance may be varied to change the resonant frequency of the circuit of the coil from the recharge frequency to another frequency to reduce the power being received. Other power management features may additionally or alternatively be employed. For instance, the device may send an uplink telemetry signal to an external device to request that recharge power be decreased. The device may switch additional resistance into the circuit of the coil to reduce the Q of the circuit. As another example, the device may clamp the circuit of the coil to ground.

Claims

1. An implantable medical device, comprising:

a tank circuit comprising a variable reactance;

a battery;

a rectifier between the battery and the tank circuit;

a controller in electrical communication with the variable reactance, the controller comprising logic that sets the variable reactance to a first value when receiving recharge energy and sets the variable reactance to a second value upon detecting an overcharge condition while receiving recharge energy; and

medical circuitry in electrical communication with the battery.

2. The implantable medical device of claim 1, wherein the tank circuit comprises a coil and wherein the variable reactance comprises a variable capacitance.

3. The implantable medical device of claim 2, wherein the variable capacitance comprises:

a first capacitor;

a second capacitor;

a switch that places the second capacitor in a parallel relationship with the first capacitor when in a first state, the controller being in electrical communication with the switch.

4. The implantable medical device of claim 3, wherein when the controller is not operational, the switch is in a state that sets the variable capacitance to tune the tank circuit for receiving telemetry signals, the implantable medical device further comprising at least one switch coupled to the tank circuit that the controller closes when receiving telemetry signals, the at least one switch being in the open state when the controller is not operational so that telemetry signals are received by the rectifier and provided as recharge energy to the battery.

5. The implantable medical device of claim 2, further comprising a first voltage limiter coupled directly to the coil and a second voltage limiter coupled directly to the variable capacitance.

6. The implantable medical device of claim 2, further comprising a capacitor low side switch coupled between the variable capacitance and ground and a inductor low side switch coupled between the coil and ground.

7. The implantable medical device of claim 6, wherein the controller closes the capacitor low side switch and the inductor low side switch upon detecting the overcharge condition.

8. The implantable medical device of claim 2, further comprising a circuit pathway including a switch in series with a resistor, the circuit pathway being in parallel with the coil.

9. The implantable medical device of claim 8, wherein the controller comprises logic to set the switch of the circuit pathway to a first state while the overcharge condition is undetected, and to set the switch of the circuit pathway to a second state upon detecting the overcharge condition.

10. The implantable medical device of claim 9, further comprising:

a set of switches coupled to opposite sides of the tank circuit, and wherein the controller puts the set of switches in a first state to ring the tank circuit when detecting the overcharge condition while receiving recharge energy.

11. The implantable medical device of claim 2, further comprising a set of switches coupled to each end of the tank circuit and wherein none of the switches of the set are coupled to a node between the coil and the variable capacitance.

12. The implantable medical device of claim 1, wherein the rectifier is a full-wave rectifier.

13. The implantable medical device of claim 12, wherein the rectifier comprises a first pair of diodes allowing current flowing through the tank circuit in a first direction to be directed to the battery and a second pair of diodes allowing current flowing through the tank circuit in a second direction to be directed to the battery.

14. The implantable medical device of claim 12, wherein the rectifier comprises a first diode and a first synchronized switch allowing current flowing through the tank circuit in a first direction to be directed to the battery and a second diode and a second synchronized switch allowing current flowing through the tank circuit in a second direction to be directed to the battery.

15. The implantable medical device of claim 1, further comprising a recharge limiter in series with the battery.

16. The implantable medical device of claim 15, further comprising a filter capacitor in parallel with the recharge limiter and battery.

17. The implantable medical device of claim 1, further comprising a switch between one side of the rectifier and ground, the controller setting the switch to an open state to provide full wave rectification and setting the switch to a closed state to provide half wave rectification.

18. The implantable medical device of claim 1, wherein the tank circuit comprises a first coil portion and a second coil portion, wherein the variable reactance comprises a variable capacitance that comprises:

a first capacitor;

a second capacitor;

a switch that places the second capacitor in a parallel relationship with the first capacitor when in a first state, the controller being in electrical communication with the switch, wherein a first node of the second capacitor is connected to between the first coil portion and the second coil portion and a second node of the second capacitor is connected to the switch.

19. The implantable medical device of claim 1, wherein the tank circuit comprises a capacitor and a variable inductance.

20. The implantable medical device of claim 19, wherein the variable inductance comprises:

a first coil portion;

a second coil portion; and

a switch that places the second coil portion in a parallel relationship with the first coil portion when in a first state, the controller being in electrical communication with the switch.

21. An implantable medical device, comprising:

a tank circuit comprising a variable reactance;

a battery;

a rectifier between the battery and the tank circuit;

a controller in electrical communication with the variable reactance, the controller comprising logic to set the variable reactance to a first value when receiving recharge energy and to set the variable reactance to a second value upon detecting an overcharge condition while receiving recharge energy; and

medical circuitry in electrical communication with the battery,

wherein the tank circuit comprises a first coil portion and a second coil portion,

wherein the variable reactance comprises a variable capacitance that comprises;

a first capacitor;

a second capacitor; and

a switch that places the second capacitor in a parallel relationship with the first capacitor when in a first state, the controller being in electrical communication with the switch, wherein a first node of the second capacitor is connected between the first coil portion and the second coil portion and a second node of the second capacitor is connected to the switch.

22. An implantable medical device, comprising:

a tank circuit comprising a variable reactance;

a battery;

a rectifier between the battery and the tank circuit;

a controller in electrical communication with the variable reactance, the controller comprising logic to set the variable reactance to a first value when receiving recharge energy and to set the variable reactance to a second value upon detecting an overcharge condition while receiving recharge energy; and

medical circuitry in electrical communication with the battery,

wherein the tank circuit comprises a capacitor and a variable inductance, wherein the variable inductance comprises;

a first coil portion;

a second coil portion; and

a switch that places the second coil portion in a parallel relationship with the first coil portion when in a first state, the controller being in electrical communication with the switch.