Patent ID: 9219473
Filing Date: 2015-12-22
Classification: G06F,H02H,H03K,H05K

Abstract:
1. A circuit, comprising: a plurality of first transistors connected in series between a pad and ground; a plurality of second transistors connected in series between the pad and a supply voltage; at least one of: a first resistance element connected in series with a drain of one of the first transistors and ground; and a second resistance element connected in series with a drain of one of the second transistors and the supply voltage; and a control circuit that applies respective bias voltages to each one of the plurality of first transistors and to each one of the plurality of second transistors, the control circuit comprising a voltage divider, wherein the bias voltages are configured to: turn off the plurality of first transistors and turn off the plurality of second transistors when a pad voltage of the pad is within a nominal voltage range; sequentially turn on the plurality of first transistors when the pad voltage increases above the nominal voltage range; and sequentially turn on the plurality of second transistors when the pad voltage decreases below the nominal voltage range.