| 摘要 |
A shock sound prevention circuit which provides a BTL audio amplifier with stable operation about 100 msec after turning-on of a power supply is required. Since the BTL audio amplifier is usually integrated in an IC, use of capacitors which takes up a large pattern area on the IC chip needs to be minimized. This invention offers a shock sound prevention circuit which has a capacitance for reference voltage to generate a reference voltage which rises according to turning-on of a power supply, a first operational amplifier to which an audio signal input and the reference voltage are applied, a second operational amplifier to which a reverse signal of the audio signal input and the reference voltage are applied, a first and a second buffers to which the reference voltage is applied and a level comparator which compares a voltage of the power supply with the reference voltage.
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