OVER VOLTAGE TOLERANT CIRCUIT

摘要

An apparatus includes an integrated circuit, which includes a processor core, a plurality of input/output (I/O) circuits, and a plurality of over voltage tolerant (OVT) circuits. Each I/O circuit is associated with an I/O pad and is associated with an OVT circuit of the plurality of OVT circuits. At least one of the OVT circuits includes a passive circuit, which is adapted to receive a pad voltage from the associated I/O pad; receive a supply voltage of the associated I/O circuit; and based on a relationship of the received pad voltage relative to the received supply voltage, selectively couple a gate of a transistor of the associated I/O circuit to the pad voltage to inhibit a leakage current.

主权项

1. A method comprising:
using a transistor of an input/output (I/O) circuit of an integrated circuit to couple an I/O pad of the integrated circuit to the I/O circuit; and inhibiting a leakage current in the transistor due to a voltage of the pad exceeding a supply voltage of the integrated circuit, wherein the transistor comprises a control terminal and inhibiting the leakage current comprises:
coupling a control terminal of a switch to the supply voltage, wherein the coupling occurs during at least during a first state of the switch in which the switch is deactivated;activating the switch in response to the voltage of the pad exceeding the supply voltage to transition the switch from the first state to a second state in which the switch couples the control terminal of the transistor to the voltage of the pad;using a comparator to compare the voltage of the pad to the supply voltage,wherein:
the comparator comprises a first input terminal, a second input terminal and an output terminal; andusing the comparator to compare the voltage of the pad to the supply voltage comprises coupling the first input terminal to the voltage of the pad and coupling the second input terminal to the supply voltage such that an input voltage between the first input terminal and the second input terminal represents the difference between the voltage of the pad and the supply voltage both when the voltage of the pad is less than the supply voltage and when the voltage of the pad is greater than the supply voltage; andcoupling the output terminal of the comparator to a substrate associated with the transistor.