CURRENT LEAKAGE DETECTION METHOD AND DEVICE

• US 20120191160A1
• Filed: 08/24/2007
• Published: 07/26/2012
• Est. Priority Date: 08/25/2006
• Status: Active Grant

• Current Assignee: Cochlear Limited
• Original Assignee: Cochlear Limited
• Inventors: Eder, Helmut Christian, Moghe, Yashodhan
• Granted Patent: US 9,238,140 B2
• Time in Patent Office: Days
• US Class Current: 607/57
• CPC Class Codes: A61N 1/3706 Pacemaker parameters stimulation threshold A61N1/371
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults

Abstract

An improved arrangement for detecting DC current leakage in implanted devices is disclosed. Currents are monitored, so that any unexpected imbalance indicates that a fault condition has occurred. The principle of the system is that if everything working correctly, the same current should be flowing into the tissue from VDDH-ELEC as is passing out of the tissue into VSS_ELEC. Any difference is indicative of current flowing into or out of the tissue from unknown paths, which is indicative of some fault. This replaces routine monitoring for specific faults.

Claims

1. A method of detecting DC current leakage in an electrical circuit of an implanted device, said method including at least the steps of:

a) measuring, for each intended current path connected to one or more predetermined points in the circuit, the current flow relative to the direction of the point;

b) summing each measured current flow to provide a total current;

c) determining whether the total current is within a predetermined margin of zero;

wherein if the total current is not within said predetermined margin of zero, determining that leakage current is present.

2. The method according to claim 1, wherein the current measurement is made by a current mirroring device.

3. The method according to claim 2, wherein the current mirroring device uses a bipolar current mirror.

4. The method according to claim 2, wherein the current mirroring device uses a MOS current mirror.

5. The method according to claim 1, wherein the currents are measured using the respective outputs of current DACs.

6. The method according to claim 1, wherein the implanted device is an implantable hearing device.

7. The method according to claim 6, wherein the implanted device is a cochlear implant and the predetermined points are electrodes of the cochlear implant.

8. The method according to claim 1, wherein if it is determined that current leakage is present, the method further includes the step of triggering a software diagnostic process.

9. The method according to claim 1, wherein if it is determined that current leakage is present, the method further includes the step of providing an indication of the current leakage.

10. A method of detecting DC current leakage in an implanted device, said device including electrical output driving circuits powered by a respective power and ground rail, said method including at least the steps of:

a) measuring a first current passing through the power rail;

b) measuring a second current passing through the ground rail;

c) comparing the first and second current measurements; and

if there is an absolute difference greater than a predetermined margin between first and second measurements, determining that current leakage is present.

11. The method according to claim 10, wherein the first and second current measurements are made by a current mirroring device.

12. The method according to claim 10, wherein the first and second currents are measured using the respective outputs of current DACs.

13. The method according to claim 11, wherein the implanted device is an implantable hearing device.

14. The method according to claim 13, wherein the implanted device is a cochlear implant.

16. The implantable device according to claim 11, wherein the implanted device is an implantable hearing device.

17. The implantable device according to claim 12, wherein the implanted device is a cochlear implant.

15. An implantable device including electrical output driving circuits powered by a respective power and ground rail, a first current monitoring device for the power rail, a second current monitoring device for the ground rail, and a comparator for comparing the first and second current monitoring device, such that if the comparator detects a difference greater than a predetermined margin, an indication is provided that current leakage is occurring.

18. An implantable device including electrical output driving circuits powered by a respective power and ground rail, a first current DAC controlling current in the power rail, a second current DAC controlling current in the ground rail, and a digital comparator for comparing the first and second DAC current values, such that if the comparator detects an absolute difference greater than a predetermined margin, an indication is provided that current leakage is occurring.

19. (canceled)