Power amplifying apparatus and audio system

摘要

The power amplifying apparatus includes a first comparator that compares the first detection signal and the fourth detection signal and outputs a first comparison signal depending on whether or not a difference between the first current and the fourth current is equal to or greater than a first predetermined value. The power amplifying apparatus includes a second comparator that compares the second detection signal and the third detection signal and outputs a second comparison signal depending on whether or not a difference between the second current and the third current is equal to or greater than a second predetermined value.

主权项

1. A power amplifying apparatus, comprising:
an amplifier that amplifies an input signal input to an input terminal to produce a first amplified signal and a second amplified signal and outputs the first amplified signal at a positive-phase output terminal and the second amplified signal at a negative-phase output terminal; a first amplifying circuit that has a first output transistor that is connected at a first end thereof to a power supply line to which a power supply potential is applied and at a second end thereof to a first output terminal at which a first output signal is output, a first current detecting circuit that detects a first current flowing through the first output transistor and outputs a first detection signal based on a result of the detection to a first detection terminal, a second output transistor that is connected to the first output terminal at a first end thereof and at a second end thereof to a ground line to which a ground potential is applied, a second current detecting circuit that detects a second current flowing through the second output transistor and outputs a second detection signal based on a result of the detection to a second detection terminal, and a first driving circuit that performs a control depending on the first amplified signal so that the first output transistor and the second output transistor are turned on and off in a complementary manner; a second amplifying circuit that has a third output transistor that is connected at a first end thereof to the power supply line and at a second end thereof to a second output terminal at which a second output signal is output, a third current detecting circuit that detects a third current flowing through the third output transistor and outputs a third detection signal based on a result of the detection to a third detection terminal, a fourth output transistor that is connected to the second output terminal at a first end thereof and to the ground line at a second end thereof, a fourth current detecting circuit that detects a fourth current flowing through the fourth output transistor and outputs a fourth detection signal based on a result of the detection to a fourth detection terminal, and a second driving circuit that performs a control depending on the second amplified signal so that the third output transistor and the first output transistor are turned on and off in a complementary manner and the third output transistor and the fourth output transistor are turned on and off in a complementary manner; a first comparator that compares the first detection signal and the fourth detection signal and outputs a first comparison signal depending on whether or not a difference between the first current and the fourth current is equal to or greater than a first predetermined value; and a second comparator that compares the second detection signal and the third detection signal and outputs a second comparison signal depending on whether or not a difference between the second current and the third current is equal to or greater than a second predetermined value.