Speaker drive integrated circuit

A speaker drive integrated circuit comprising:

• a power supply terminal and a GND terminal, each connected to an external power supply;
• an input terminal to which an audio signal is input;
• two output terminals respectively connected to both ends of a speaker;
• an amplifying circuit including a first amplifier and a second amplifier and capable of setting an output side thereof to a high impedance state during a non-operating period, the first amplifier being configured to amplify the audio signal input to the input terminal and output the amplified audio signal through one of said two output terminals, the second amplifier being configured to invert a phase of the audio signal, amplify the phase-inverted audio signal, and output the amplified audio signal through the other output terminal;
• a switching power supply circuit configured to boost a voltage of the external power supply connected to the power supply terminal and the GND terminal such that an output of the amplifying circuit becomes a predetermined voltage necessary for driving the speaker;
• a standby circuit configured to selectively set the amplifying circuit between an operating state and a nonoperating state where the output side is in the high impedance state;
• a load connection status detecting circuit configured to cause a current to flow from the external power supply to one of said two output terminals when the standby circuit sets the amplifying circuit to the nonoperating state where the output side is in the high impedance state and detect whether a load connection status of the speaker with respect to said two output terminals is normal, open, or short based on a voltage generated at said one of said two output terminals by the current;
• and
• a transmitting terminal through which a signal indicating a detection result by the load connection status detecting circuit is output to outside.