| 摘要 |
This speaker protection circuit includes: a voltage comparator that compares a voltage of a reference bias terminal of an amplifying circuit constituting a BTL amplifying device with a preset threshold voltage; and first and second switches for switching between a mode of supplying an electric current to each of two power amplifying circuits and a mode of cutting off the electric current. When the voltage of the reference bias terminal is lower than the threshold voltage, based on an output level of the voltage comparator, at least one of the first and second switches is turned off to cut off a current supply to each of the power amplifying circuits so that driving of a speaker by the power amplifying circuits is halted. Thus, it is possible to suppress, using a relatively simple configuration, an offset current generated in a speaker due to an abnormality of the voltage of a reference bias terminal.
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