PURPOSE: A judgement circuit is provided to accurately judge a kind of connected instrument through a first detection unit, a second detection unit and a judgement unit.;CONSTITUTION: A power detection circuit(50) detects whether the power supply voltage Vbus of a terminal VB1 is applied to a terminal VB2 based on the voltage of the terminal VB2. An identification voltage detection circuit(51) acquires voltage varying with identification resistance of a cable connected to a terminal ID2. A control circuit(56) controls a voltage application circuit(52,53) based on the detection result of the power detection circuit and the identification voltage detection circuit. The voltage application circuit is a circuit applying power voltage Vdd to a terminal DP2 or ground voltage to a device having a predetermined impedance by disposing, and consists of a power source(70), a resistor(71) and a switch(72). The voltage application circuit as the voltage application circuit is a circuit applying the power voltage Vdd to a terminal DM2 or the ground voltage through a device having a predetermined impedance based on a control signal CNT2 from the control circuit, and includes a resistor and a switch. A judgement circuit(54) judges a type of a connected instrument to a portable device and outputs the judgement data showing the judgement result to the control circuit. An IF circuit exchanges various information between a CPU and the control circuit. The control circuit integrally controls each block of the judgement circuit when and if the power detection circuit detects the connection of the terminal VB1 and VB2.;COPYRIGHT KIPO 2013;[Reference numerals] (30) Determination circuit; (50) Power detection circuit; (51) Identification voltage detection circuit; (54) Judgement circuit; (55) IF circuit; (56) Control circuit; (AA) Command from a CPU(33); (BB) Judgement data, Identification data; (CC) Judgement data/Conversion command; (DD) Identification data
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