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Part Number: UCC28950
Dear Sir about the previous circuit, PMP-6712, after the actual board test, found a problem, that is, the output voltage of 330V can not be stabilized, its output voltage will rise to OVP (set 350V), I suspect the circuit There is something wrong with the resistance, please ask your help to solve the problem.The difference between our application and the PMP-6712 circuit:1 The output is high voltage, so you are recommended to use a diode instead of a synchronous rectified FET. Therefore, UCC-28950 out-E out-F is connected to a resistor 13K to ground.2 Because the output is high voltage, you are also recommended to use a 12V power supply in the transformer to provide Photocupler and TL-431 VCC applications. After testing, the Photocupler has normal operation, and the resistance of pin 3.4 is 4K12 when it is turned on.3 UCC-28950 OPTO-E=4.88V, EA-=2.5V EA+=2.496V, is this condition in line with the specifications?4 Photocupler and TL-431 The power supply is only provided by another group of 12V transformers, and there is no additional LM-5017 isolated power supply. Is this OK?5 The board layout adopts 4 layers. If Top-layout has Polygon, can it be connected directly to Input Ground? Can the same inner layer (2.3 Midlayout) Polygon be directly connected to Input Ground?6 In addition to this circuit, is there any place we should pay attention to? Thank You Dick Liu 11/8/2018
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In reply to Peter Meaney:
In reply to Taiwan:
Can you send me your schematic in pdf format and the PCB Gerber files to my email address and I can review them.
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