| 摘要 |
A control circuit is provided for an auxiliary power supply in an apparatus having run and standby modes of operation. The auxiliary power supply is energized by raw B+ voltage and operates in a switched mode, responsive to a feedback signal indicative of loading. A switching circuit, also energized by the raw B+ voltage, changes the auxiliary power supply between operational and non operational modes responsive to an on/off signal. The on/off signal is indicative of the run and standby modes of operation of the apparatus, for example a run supply voltage generated by another power supply in the apparatus. The switching circuit includes a switch optically coupled to a voltage threshold detector. The switch interrupts the feedback signal, for example by shunting to ground, in a manner which inhibits operation of the switching controller during the standby mode of operation of the apparatus.
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