The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Date of Patent:
Jul. 20, 1999

Filed:

Aug. 19, 1993
Applicant:
Inventors:

Robert Rountree, Plano, TX (US);

Charvaka Duvvury, Plano, TX (US);

Tatsuroh Maki, Ami-Machi, JP;

Assignee:
Attorneys:
Primary Examiner:
Int. Cl.
CPC ...
H01L / ;
U.S. Cl.
CPC ...
257536 ; 257173 ; 361 56 ;
Abstract

An input protection device is presented having a depletion controlled isolation stage. In one embodiment of the invention, a depletion controlled isolation resistor is formed between adjacent N+ diffused regions by N-well diffusion. One N+ diffused region electrically contacts an input bond pad and a primary protective device. The other N+ diffused region electrically contacts a second protective device and the internal circuit it is to protect. The depletion controlled isolation resistor limits the amount of current passing through the resistor to a safe level during an over-voltage condition. In another embodiment of the invention, a depletion controlled isolation stage includes a silicon controlled rectifier (SCR) as the primary protective device in combination with the depletion controlled isolation resistor.


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