Low voltage protection module

• US 20030010997A1
• Filed: 09/05/2002
• Published: 01/16/2003
• Est. Priority Date: 03/01/1999
• Status: Active Grant

• Current Assignee: Dimitris Jim Pelegris, Elmer L. Turner Jr, Kelly C. Casey
• Original Assignee: Dimitris Jim Pelegris, Elmer L. Turner Jr, Kelly C. Casey
• Inventors: Turner, Elmer L. Jr., Pelegris, Dimitris Jim, Casey, Kelly C.
• Granted Patent: US 6,696,709 B2
• Time in Patent Office: Days
• US Class Current: 257/173
• CPC Class Codes: H01L 27/0259 using bipolar transistors as protective elements
• CPC Class Codes: H01L 27/0262 including a PNP transistor and a NPN transistor, wherein each of said transistors has its base coupled to the collector of the other transistor, e.g. silicon controlled rectifier [SCR] devices
• CPC Class Codes: H01L 29/7424 having a built-in localised breakdown/breakover region, e.g. self-protected against destructive spontaneous, e.g. voltage breakover, firing
• CPC Class Codes: H01L 29/747 Bidirectional devices, e.g. triacs
• CPC Class Codes: H01L 29/87 Thyristor diodes, e.g. Shockley diodes, break-over diodes

Abstract

A semiconductor thyristor device incorporates buried regions to achieve low breakover voltage devices, and the buried regions are offset laterally with respect to the emitter regions. The low voltage thyristor devices can be incorporated into five-pin protection modules for protecting customer circuits.

Claims

1. A low voltage protection module, comprising:

a module base;

a plurality of pins held within said base; and

a plurality of components connected to said pins, including a low voltage thyristor connected between two of said pins, said thyristor providing overvoltage protection to external circuits connected to the pins of said module, and said thyristor formed in a semiconductor chip with a buried region having an impurity concentration defining a breakover voltage of said low voltage thyristor, and said low voltage thyristor having an emitter region formed in said semiconductor chip laterally offset from said buried region.

2. The low voltage protection module of claim 1, wherein said low voltage thyristor provides overvoltage protection in the range of between about five volts and about fifty volts.

3. The low voltage protection module of claim 1, further including a transformer providing DC isolation between input pins and output pins of said module.

4. The low voltage protection module of claim 3, further including one or more said low voltage thyristors connected in a secondary side of said transformer.

5. The low voltage protection module of claim 4, further including a first low voltage thyristor connected so as to provide low voltage overvoltage protection in the secondary side of said transformer, to ground.

6. The low voltage protection module of claim 1, further including an overvoltage protection circuit connected to said module pins, said overvoltage protection circuit including at least one positive temperature coefficient element for providing overcurrent protection, and a capacitor connected between one terminal of said positive temperature coefficient element and a ground pin of the module, and wherein said low voltage thyristor comprises a unidirectional low voltage thyristor device.

7. The low voltage protection module of claim 6, wherein said unidirectional low voltage thyristor device is formed with a diode bridging the unidirectional low voltage thyristor device.

8. The low voltage protection module of claim 6, wherein said overvoltage protection circuit defines a first circuit, and further including a second overvoltage protection circuit functioning in a manner substantially identical to said first overvoltage protection circuit, said first and second overvoltage protection circuits being connected to said pins to provide overcurrent and overvoltage protection to external customer circuits connected to ones of said pins.

9. The low voltage protection module of claim 8, wherein said module includes five pins.

10. The low voltage protection module of claim 6, wherein said unidirectional low voltage thyristor device is formed as a combination of a unidirectional thyristor in parallel with a diode, each formed in a semiconductor chip, and wherein said semiconductor chip has a pair of contacts formed on one side surface thereof, and further including a lead frame soldered to said contacts to thereby short circuit the contacts on said one side.

11. The low voltage protection module of claim 1, wherein one said component includes a transformer having a primary with two terminals thereof connected to respective pins of said module, a secondary of said transformer having two terminals connected to respective customer side pins of said module, said transformer being effective to couple AC-type signals from the transformer primary to the transformer secondary;

and

one or more of said low voltage thyristors connected to said transformer secondary to provide overvoltage protection to customer circuits connected to said customer side pins.

12. The low voltage protection module of claim 11, further including a pair of said low voltage thyristors coupled in series, and coupled between the transformer secondary terminals, and wherein a junction of said series-connected low voltage thyristors is connected to a ground pin of said module.

13. The low voltage protection module of claim 12, wherein said low voltage thyristors comprise bidirectional thyristors.