Selective potting for controlled failure and electronic devices employing the same

• US 7,460,350 B2
• Filed: 02/05/2007
• Issued: 12/02/2008
• Est. Priority Date: 04/19/2001
• Status: Expired due to Fees

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Moberg, Sheldon B., Talbot, Cary D., Yonemoto, Jay A., Causey, James D. III
• Primary Examiner(s): Jackson; Stephen W.
• Application Number:
  US11/702,713
• Publication Number:
  US 20070159755A1
• Time in Patent Office: 666 Days
• Field of Search: 361/100
• US Class Current: 361/100
• CPC Class Codes: A61M 2205/16 with back-up system in case of failure
• CPC Class Codes: A61M 2205/17 with redundant control systems
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 5/142 Pressure infusion, e.g. using pumps
• CPC Class Codes: B60R 1/12 Mirror assemblies combined with other articles, e.g. clocks
• CPC Class Codes: B60R 2001/1284 with communication systems other than radio-receivers, e.g. keyless entry systems, navigation systems; with anti-collision systems
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 7/0042 characterised by the mechanical construction
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/00 Conversion of dc power input into dc power output
• CPC Class Codes: H02M 7/003 Constructional details, e.g. physical layout, assembly, wiring or busbar connections

Abstract

A selectively protected electrical system includes or operates with a power source, a load, a power driver circuit for controllably transferring power from the power source to the load, the power driver circuit being encapsulated in a potting material, and a controller for enabling and disabling the power driver circuit, the controller being un-encapsulated by the potting material. If a contaminant induced electrical fault occurs in the selectively protected electrical system, the electrical fault is more likely to occur in the un-encapsulated controller, such that the selectively protected electrical system is disabled. The contaminant is inhibited from contacting and inducing an electrical fault in the power driver circuit, thus providing for a controlled failure of the selectively protected electrical system.

Claims

1. A system for providing electrical power to an electrical load, the system comprising:

at least one electrical load terminal for electronic connection to a load;

at least one power supply terminal for electronic connection to a power source to provide an electrical power signal on the at least one power supply terminal;

safety circuitry electrically coupled between the at least one power supply terminal and the at least one load terminal, wherein a portion of the safety circuitry is encapsulated with a material that inhibits passage of a predefined contaminant and another portion of the safety circuitry is at least partially unencapsulated to allow exposure to the contaminant when the contaminant is present in the system.

2. A system according to claim 1, wherein an electrical power signal on the at least one power supply terminal is applied to the at least one electrical load terminal when the at least partially unencapsulated portion of the safety circuitry is not exposed to the contaminant, and is disconnected from the at least one electrical load terminal upon sufficient exposure of the at least partially unencapsulated portion of the safety circuitry to the contaminant.

3. A system according to claim 1, wherein the safety circuitry is configured to connect an electrical power signal on the at least one power supply terminal to the at least one electrical load terminal when the at least partially unencapsulated portion of the safety circuitry is not exposed to the contaminant and to disconnect the electrical power signal from the at least one electrical load terminal upon sufficient exposure of the at least partially unencapsulated portion of the safety circuitry to the contaminant.

4. A system according to claim 1, wherein the at least partially unencapsulated portion of the safety circuitry includes or is connected to at least one circuit element that is dissolvable by the contaminant to disconnect the electrical power signal on the at least one power supply terminal from the at least one electrical load terminal upon sufficient exposure to the contaminant.

5. A system according to claim 4, wherein the dissolvable circuit element comprises a dissolvable fuse.

6. A system according to claim 1, wherein the at least partially unencapsulated portion of the safety circuitry includes or is connected to at least one circuit element that senses the contaminant and disconnects the electrical power signal on the at least one power supply terminal from the at least one electrical load terminal upon sufficient exposure to the contaminant.

7. A system according to claim 6, wherein the at least one circuit element that senses the contaminant comprises an humidity sensor.

8. A system according to claim 1, wherein the safety circuitry comprises:

a controller for providing the at least one control signal; and

a safety circuit for receiving the at least one control signal, wherein the safety circuit is electrically coupled to the at least one power supply terminal and to the at least one load terminal, and wherein the safety circuit is configured to connect the electrical power signal to the at least one load terminal upon receipt of the at least one control signal and to disconnect the electrical power signal from the at least one load terminal upon no receipt of the at least one control signal;

wherein the controller comprises the at least partially unencapsulated portion of the safety circuitry.

9. A system according to claim 8, wherein the safety circuit comprises the encapsulated portion of the safety circuitry.

10. A system according to claim 8, wherein the safety circuit is provided in a voltage converter.

11. A system according to claim 10, further comprising at least one Zener diode coupled between the voltage converter and at least one electrical load terminal.

12. A system according to claim 11, further comprising a Schottky diode coupled in parallel to the at least one Zener diode.

13. A system according to claim 11, wherein said at least one Zener diode comprises first and second Zener diodes coupled in series, the second Zener diode being coupled in reverse biased arrangement relative to the first Zener diode.

14. A system according to claim 1, further comprising an electrical load coupled to the at least one electrical load terminal, the electrical load comprises a drive motor coupled to a medical infusion pump.

15. A system according to claim 1, wherein the material that encapsulates a portion of the safety circuitry to inhibit passage of a predefined contaminant comprises a potting material.

16. A method of coupling a system for providing electrical power to an electrical load, the method comprising:

electrically connecting at least one electrical load terminal to a load;

electrically connecting at least one power supply terminal to a power source to provide an electrical power signal on the at least one power supply terminal;

electrically connecting safety circuitry between the at least one power supply terminal and the at least one load terminal; and

encapsulating a portion of the safety circuitry with a material that inhibits passage of a predefined contaminant, and maintaining another portion of the safety circuitry at least partially unencapsulated to allow exposure to the contaminant when the contaminant is present in the system.

17. A method according to claim 16, further comprising configuring the safety circuitry to allow an electrical power signal on the at least one power supply terminal to be applied to the at least one electrical load terminal when the unencapsulated portion of the safety circuitry is not exposed to the contaminant and to disconnect the electrical power signal on the at least one power supply terminal from the at least one electrical load terminal upon sufficient exposure of the unencapsulated portion of the safety circuitry to the contaminant.

18. A method according to claim 16, further comprising applying an electrical power signal on the at least one power supply terminal to the at least one electrical load terminal when the at least partially unencapsulated portion of the safety circuitry is not exposed to the contaminant, and disconnecting the electrical power signal from the at least one electrical load terminal upon sufficient exposure of the at least partially unencapsulated portion of the safety circuitry to the contaminant.

19. A method according to claim 16, further comprising connecting or including at least one dissolvable circuit element in the at least partially unencapsulated portion of the safety circuitry, wherein the at least one dissolvable circuit element is dissolvable by the contaminant to disconnect the electrical power signal on the at least one power supply terminal from the at least one electrical load terminal upon sufficient exposure of the dissolvable circuit element to the contaminant.

20. A method according to claim 19, wherein the dissolvable circuit element comprises a dissolvable fuse.

21. A method according to claim 18, wherein the at least partially unencapsulated portion of the safety circuitry includes or is connected to at least one circuit element that senses the contaminant and disconnects the electrical power signal on the at least one power supply terminal from the at least one electrical load terminal upon sufficient exposure of the at least one circuit element to the contaminant.

22. A method according to claim 21, wherein the at least one circuit element that senses the contaminant comprises an humidity sensor.

23. A system connectable to a power source and an electrical load, for providing electrical power to the electrical load, the system comprising a safety circuitry configured to be electrically coupled between the power source and the load, wherein a portion of the safety circuitry is encapsulated with a material that inhibits passage of a predefined contaminant and another portion of the safety circuitry is unencapsulated to allow exposure to the contaminant when the contaminant is present in the system, and wherein the safety circuitry is configured to connect electrical power from the power source to the electrical load when the unencapsulated portion of the safety circuitry is not exposed to the contaminant and to disconnect electrical power from the electrical load upon sufficient exposure of the unencapsulated portion of the safety circuitry to the contaminant.