Texas Instruments Corporation

Tatsuroh Maki

Charvaka Duvvury

Robert N Rountree

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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Amimachi, Japan

Tatsuroh Maki