Apparatus and method for detecting foreign substance

An apparatus for detecting a foreign substance or a device on a connector including at least a first pin, wherein the apparatus comprises:

• a current source, wherein the current source supplies detection currents to the at least first pin of the connector, wherein the detection currents are set at different levels;
• a detection circuit, wherein the detection circuit detects a voltage on the first pin;
• and
• a detection controller,
• wherein the detection controller controls the different levels of the detection currents supplied to the first pin and supply time points, and wherein the detection controller detects the foreign substance or the device attached to the connector by measuring the input voltage on the first pin from the detection circuit,
• wherein the detection circuit measures both of a second voltage (VS2) on the first pin for a second current (I2) and a third voltage (VS3) on the first pin for a third current (I3) that is different from the second current (I2) by sequentially supplying the second current (I2) and the third current (I3) to the first pin through the current source via the connection state determination subroutine;
• wherein the detection controller determines whether or not a substance attached to the first pin is a resistance component based on comparison of a ratio of the second current (I2) to the third current (I3) and a ratio of the second voltage (VS2) to the third voltage (VS3);
• and
• wherein the detection controller starts a rated device determination subroutine that determines that a rated device is connected to the first pin when the substance is the resistance component and determines that a rated device is not connected to the first pin when the substance is not the resistance component.