| 摘要 |
PURPOSE:To prevent the destruction at the failed connection to the power supply by turning off an amplifier stage by an output voltage when an output terminal of an output stage in push-pull connection driven by the amplifier stage is higher than a reference potential. CONSTITUTION:An output of an amplifier circuit 1 before the output stage including the 1st stage is fed to output transistors (TRs) 3, 4. Let a potential of a power terminal 5 be Vcc and the voltage of a voltage source 6 be V6, then a comparator 7 compares a voltage Vout of an output terminal 2 with a voltage (Vcc-V6), and cuts off a drive circuit of the TR 4 at Vout>(Vcc-V6). Thus, the TR 4 is turned off if it is connected in failure to the power supply thereby preventing the output TR from being destroyed.
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