Battery protection and zero-volt battery recovery system for an implantable medical device

• US 10,118,045 B2
• Filed: 06/16/2017
• Issued: 11/06/2018
• Est. Priority Date: 12/07/2005
• Status: Expired due to Fees

• Current Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Inventors: He, Yuping, Peterson, David K. L.
• Primary Examiner(s): Wehrheim, Lindsey G
• Application Number:
  US15/625,892
• Publication Number:
  US 20170281950A1
• Time in Patent Office: 508 Days
• CPC Class Codes: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: A61N 1/378 Electrical supply
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Circuitry useable to protect and reliably charge a rechargeable battery, even from a zero-volt state, is disclosed, and is particularly useful when employed in an implantable medical device. The circuit includes two charging paths, a first path for trickle charging the battery at a relatively low current when the battery voltage is below a threshold, and a second path for charging the battery at relatively higher currents that the battery voltage is above a certain threshold. A passive diode is used in the first trickle-charging path which allows trickle charging even when the battery voltage is too low for reliable gating, while a gateable switch (preferably a PMOS transistor) is used in the second higher-current charging path when the voltage is higher and the switch can therefore be gated more reliably. A second diode between the two paths ensures no leakage to the substrate through the gateable switch during trickle charging. The load couples to the battery through the switch, and preferably through a second switch specifically used for decoupling the load.

Claims

1. A circuit for an implantable medical device, comprising:

a rechargeable battery with a battery terminal and a grounded terminal, the battery terminal for producing a battery voltage;

a first charging path to the battery terminal, wherein the first charging path passes from a first node through at least one first diode to the battery terminal;

a second charging path to the battery terminal, wherein the second charging path comprises first switching circuitry coupled between a second node and the battery terminal; and

at least one second diode coupled between the first node and the second node,

wherein the at least one second diode is configured to bias the second node to the battery voltage when the first charging path is active to pass a current to the battery.

2. The circuit of claim 1, further comprising a controller configured to turn off the first switching circuitry to deactivate the second charging path.

3. The circuit of claim 1, further comprising a load coupled to the second charging path through second switching circuitry.

4. The circuit of claim 3, wherein the second switching circuitry is coupled between the second node and the load.

5. The circuit of claim 1, wherein the at least one first diode is forward biased from the first node to the battery terminal.

6. The circuit of claim 5, wherein the at least one second diode is forward biased from the first node to the second node.

7. The circuit of claim 1, wherein the first switching circuitry consists of a PMOS transistor.

8. The circuit of claim 7, wherein a well of the PMOS transistor is biased to a higher of a source or a drain of the PMOS transistor.

9. The circuit of claim 7, wherein a well of the PMOS transistor is coupled to the battery terminal.

10. The circuit of claim 7, wherein a well of the PMOS transistor is biased to a voltage on the second charging path.

11. The circuit of claim 1, further comprising a controller configured to open the first switching circuitry when a voltage of the battery is below a threshold voltage, and configured to close the first switching circuitry when the voltage of the battery is above a threshold voltage.

12. The circuit of claim 1, further comprising charge controller circuitry, wherein the first node and the second node are connected to outputs of the charge controller circuity.

13. A method for recharging a battery in an implantable medical device, comprising:

producing a first current to charge the battery through a first path when the battery voltage is greater than or equal to zero and less than or equal to a threshold; and

producing a second current to charge the battery through a second path when the battery voltage is greater than the threshold, wherein the second current is larger than the first current,

wherein there is at least one second diode forward biased from the first path to the second path.

14. The method of claim 13, wherein the second path is comprises switching circuitry to control the second current through the second path.

15. The method of claim 14, wherein the first path comprises only one or more passive components.

16. The method of claim 15, wherein the one or more passive components comprise one or more first diodes forward biased through the first path to the battery.

17. The method of claim 14, wherein the switching circuitry consists of a PMOS transistor.

18. The method of claim 14, wherein the switching circuitry is deactivated when excessive discharge from the battery is detected.

19. The method of claim 14, wherein the switching circuitry is deactivated when the battery is being charged through the first path.

20. The method of claim 13, wherein the battery is a lithium-ion battery or a lithium-ion polymer battery.