State detection circuit for detecting tri-state and state detection method thereof

A state detection circuit configured to detect whether a coupling state of an input node is floating, electrically connected to a ground potential, or electrically connected to an external voltage, wherein the state detection circuit comprises:

• a unidirectional-conductive device, configured to unidirectionally conduct from a test node to a detection node, the detection node being coupled to the input node, wherein a current path is formed by the test node, the unidirectional-conductive device, the detection node, and the input node, wherein the voltage across the unidirectional-conductive device, when conducting, is a forward conduction voltage;
• a voltage generation circuit, configured to generate and control a voltage at the test node to a high potential during a detection stage, wherein a voltage level of the detection node is determined according to the coupling state of the input node, the high potential, the conduction state of the unidirectional-conductive device, and the forward conduction voltage;
• and
• a determination circuit, configured to determine the coupling state of the input node in the detection stage according to at least one of the following conditions:
• (1) when the voltage level of the detection node is less than a first threshold and greater than a second threshold, the determination circuit determines that the coupling state of the input node is floating;
• (2) when the voltage level of the detection node is less than the second threshold, the determination circuit determines that the coupling state of the input node is electrically connected to the ground potential;
• and/or
• (3) when the voltage level of the detection node is greater than the first threshold, the determination circuit determines that the coupling state of the input node is electrically connected to the external voltage;
• wherein the external voltage is greater than or equal to the voltage at the test node, wherein the first threshold is greater than the second threshold.