4 , the main power circuit voltage process

 

R91, R86, R87 voltage divider consisting of sampling circuit, when the +24 V voltage increases , after the partial pressure to the U5 (TL431) (1) foot , U5 (3) pin voltage is low , U11 (PC817) optocoupler guide through the Ul (NCP1377B) main power chip ( 2 ) feet potential low power chip output PWM duty cycle decreases. V2 (MOS) conduction time becomes shorter , so that the transformer secondary voltage is reduced , the process regulator is completed .

 

+2 4V voltage regulator circuit to reduce the process time to work with the above process is reversed .

 

5 , the main power circuit overcurrent detection

 

When something causes V2 MOS tube current increases . R60, the voltage drop across resistor R61 increases , the voltage supplied by R20 Ul (3) current detection terminal pin , when ( 3 ) chip pin voltage rises to the threshold voltage . Ul main power chip to stop vibration , thus avoiding V2 overcurrent damage.

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