OPA2374: The output increase suddenly

aggil liang

Part Number: OPA2374

Hi Team

My customer use OPA2374 for the PFC current senseing in a power mode. When the PFC MOSFET Q7-1 turn off, the output of opa2374 is increased suddenly, and it is not normally. Below is the schematic and test waveform. Pls. help to give some suggestion. thanks

over 5 years ago

0 kai klaas69 over 5 years ago

Guru 140200 points

Hi Aggli,

C40 looks weird! Remove it and place a 10p cap in parallel with R51. If the low pass filtering effect is too little, increase this cap and C39, but keep the both caps identical. Otherwise the common mode rejection of this difference amplifier will degrade.

Take care, the common mode input voltage range of OPA2374 is only 0.2V below GND. If you violate this specification the OPA2374 will stop working properly.

Kai

0 aggil liang over 5 years ago in reply to kai klaas69

Expert 2660 points

Hi Kai
thank you for your comment, and we will try. we will update the result to you later.

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OPA2374: The output increase suddenly