Electrostatic discharge apparatus for network devices

• US 7,035,072 B2
• Filed: 07/10/2002
• Issued: 04/25/2006
• Est. Priority Date: 07/10/2001
• Status: Expired due to Fees

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Littlefuse Incorporated
• Inventors: Colby, James A.
• Primary Examiner(s): Huynh, Kim
• Assistant Examiner(s): Nguyen, Tanh Q.
• Application Number:
  US10/192,314
• Publication Number:
  US 20030011026A1
• Time in Patent Office: 1,385 Days
• Field of Search: 361/111, 361/56, 361/127, 361/119, 361/118, 338/20, 338/21
• US Class Current: 361/118
• CPC Class Codes: H01R 13/6485 Electrostatic discharge protection in general H05F1/00, for electric apparatus H05K9/0067
• CPC Class Codes: H01R 13/6666 with built-in overvoltage protection
• CPC Class Codes: H02H 9/04 responsive to excess voltage lightning arrestors H01C7/12, H01C8/04, H01G9/18, H01T
• CPC Class Codes: H04M 3/18 with means for reducing interference or noise; with means for reducing effects due to line faults with means for protecting lines
• CPC Class Codes: H05K 1/0259 Electrostatic discharge [ESD] protection
• CPC Class Codes: H05K 1/0393 Flexible materials H05K1/038 takes precedence; specific organic compositions are classified in H05K1/0313 and subgroups
• CPC Class Codes: H05K 1/162 incorporating printed capacitors
• CPC Class Codes: H05K 1/167 incorporating printed resistors
• CPC Class Codes: H05K 1/18 Printed circuits structurally associated with non-printed electric components H05K1/0201, H05K1/023, H05K1/0243, and H05K1/16 take precedence
• CPC Class Codes: H05K 2201/0738 Use of voltage responsive materials, e.g. voltage switchable dielectric or varistor materials
• CPC Class Codes: H05K 2201/10015 Non-printed capacitor
• CPC Class Codes: H05K 2201/10022 Non-printed resistor
• CPC Class Codes: H05K 9/0066 Constructional details of transient suppressor

Abstract

The present invention provides an ESD apparatus that includes an electrical overstress suppression device in series with a capacitor. The ESD apparatus is ideally suited for use with network communication devices, but any electronic device requiring overvoltage protection and isolation may employ the ESD apparatus of the present invention. In one embodiment, the ESD apparatus includes a capacitor and an electrical overstress protection device that electrically communicates in series with the capacitor. In another embodiment, the ESD apparatus includes an electrical overstress protection device having a voltage variable material and a capacitor that electrically communicates in series with the overstress protection device. The capacitor is sized so that the overstress device can withstand an application of a predetermined steady state voltage.

Claims

1. An electrostatic discharge (“

ESD”

) apparatus comprising;

an electrostatic discharge circuit configured to withstand a steady state signal, the circuit including;

an electrical overstress protection device having a polymeric non-ohmic voltage variable material, the voltage variable material susceptible to failure if the steady state signal reaches 2250 Volts DC; and

a capacitor that electrically communicates in series with the protection device, the capacitor configured and arranged to protect the electrical overstress protection device from the high voltage steady state signal.

2. The ESD apparatus of claim 1, which includes a signal line that electrically couples to one of the EOS protection device and the capacitor.

3. The ESD apparatus of claim 2, wherein the signal line is selected from a group consisting of 10BaseT, 100BaseT and 1000BaseT data lines.

4. The ESD apparatus of claim 2, which includes an Ethernet network device that electrically communicates with the signal line.

5. The ESD apparatus of claim 2, which includes a transceiver that electrically communicates with the signal line.

6. The ESD apparatus of claim 1, which includes a ground that electrically communicates with one of the EOS protection device and the capacitor.

7. The ESD apparatus of claim 1, wherein the capacitor is sized so that the EOS protection device can withstand an application of a predetermined direct current voltage.

8. The ESD apparatus of claim 1, wherein the capacitor blocks DC current that travels from a signal line to ground.

9. The ESD apparatus of claim 1, wherein the capacitor couples to an unused data line of a data transmission connector.

10. The ESD apparatus of claim 1, wherein the EOS protection device and the capacitor are affixed to a printed circuit board (“

PCB”

).

11. The ESD apparatus of claim 1, wherein the EOS protection device and the capacitor electrically communicate with at least one PCB trace, and wherein the trace communicates electrically with a data transmission connector.

12. The ESD apparatus of claim 1, wherein the capacitor additionally serves to reduce power consumption.

13. The ESD apparatus of claim 1, wherein the EOS protection device and the capacitor are affixed to a flexible circuit.

14. The ESD apparatus of claim 13, wherein the EOS protection device and the capacitor electrically communicate with a spring contact affixed to the flexible circuit.

15. The ESD apparatus of claim 13, wherein the EOS protection device and the capacitor electrically communicate with a connector pin of an electrical device.

16. The ESD apparatus of claim 13, wherein a plurality of EOS devices and capacitors electrically communicate with a plurality of contacts affixed to the flexible circuit.

17. An electrostatic discharge (“

ESD”

) apparatus comprising;

a polymeric composite voltage variable material (“

VVM”

); and

a capacitor material that electrically communicates in series with the VVM, the capacitor material sized so that the VVM can withstand an application of a predetermined steady state direct current voltage of at least 2250 volts.

18. The ESD apparatus of claim 17, wherein the VVM includes a matrix of conductive and semiconductive particles.

19. The ESD apparatus of claim 17, wherein the VVM includes irregularly shaped conductor particles having insulative oxide surface coatings that are bound in a matrix.

20. The ESD apparatus of claim 17, wherein the VVM includes a mixture of conductive and semiconductive particles having surfaces coated with an insulative oxide film, the conductive and semiconductive particles being bound together in an insulative binder.

21. The ESD apparatus of claim 17, wherein the VVM includes conductive and semiconductive particles that are coated with an insulative oxide film and that are bound together in point contact with one another.

22. The ESD apparatus of claim 17, wherein the VVM includes conductive and semiconductive particles sized to be 10 to 20 microns.

23. The ESD apparatus of claim 17, wherein the VVM self-adheres directly to a substrate.

24. The ESD apparatus of claim 17, wherein the VVM is disposed inside a housing with the capacitor material.

25. The ESD apparatus of claim 17, wherein the VVM is disposed inside a housing with a capacitor that holds the capacitor material.

26. An electrical circuit for electrostatic discharge suppression comprising:

a signal line;

a polymeric non-ohmic voltage variable material (“

VVM”

) that electrically communicates with the signal line, the VVM susceptible to failure if subjected to a steady state direct current voltage of 2,250 volts;

a capacitor that electrically communicates in series with the VVM, wherein the capacitor is configured to protect the VVM from the steady state direct current voltage; and

a ground that electrically communicates with the capacitor.

27. The electrical circuit of claim 26, which includes an Ethernet network device that electrically communicates with the signal line.

28. The electrical circuit of claim 26, wherein the capacitor additionally serves to reduce power consumption.

29. The electrical circuit of claim 26, wherein the VVM is disposed in a manner selected from the group consisting of:

in a device, on a flex circuit and applied directly to a substrate.