OVER-VOLTAGE TOLERANT CIRCUIT AND METHOD

摘要

Over-voltage tolerant circuits and methods are provided. In one embodiment, the circuit includes a pull-up transistor coupled to an I/O pad, a sensing circuit coupled to the I/O pad and to a voltage supply (Vcc), the sensing circuit configured to sense a voltage applied to the pad (Vpad), a latch coupled to the sensing circuit to retain an output of the sensing circuit, and a selection circuit coupled to the sensing circuit through the latch. The selection circuit includes a first bias circuit to apply Vcc to a well and gate of the pull-up transistor, a second bias circuit to apply Vpad to the gate and the well of the pull-up transistor, and a non-overlap circuit configured to ensure the gate and the well of the pull-up transistor is substantially always driven by either the first or the second bias circuit depending on the output of the sensing circuit.

主权项

1. A circuit comprising:
a pull-up transistor coupled to an I/O pad of an electronic device; a sensing circuit coupled to the I/O pad and to a voltage supply (Vcc), the sensing circuit configured to sense a voltage applied to the pad (Vpad); a latch coupled to the sensing circuit and configured to retain an output of the sensing circuit; and a selection circuit coupled to the sensing circuit through the latch, the selection circuit comprising:
a first bias circuit to apply Vcc to a well and gate of the pull-up transistor, and a second bias circuit to apply Vpad to the gate and the well of the pull-up transistor; anda non-overlap circuit configured to ensure the gate and the well of the pull-up transistor is substantially always driven by either the first or the second bias circuit depending on the output of the sensing circuit.