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PFCLLCSREVM034: Power management forum

Rahamadullah A
Prodigy 160 points

Part Number: PFCLLCSREVM034
Other Parts Discussed in Thread: ISOM8110

Tool/software:

Hi TI team

In PFC +LLC eval board i came across this circuit where there is a connection RVCC to the FB pin through a zener and a resistor. What is the purpose it is serving?

In place of VO618A optocoupler can i use ISOM8110 optoemulator as a drop and replacement?

If not what are the values i need to change in the same eval board. Please advice

Regards

Rahamadullah

  • 0
    TI__Guru* 86286 points

    Hello,

    Your inquiry is under evaluation and I will get back to you shortly.

    Regards,

  • 0 in reply to Mike O'
    TI__Guru* 86286 points

    Hello,

    I reviewed the design and it looks like the designer added R27 and D5 to give the opto additional bias current.  This is most likely to have a CTR ratio of the opto that is in the characterized range.

    You need to compare the VO618A and ISOM8110 data sheet to see if they have the same/similar CTR, bias currents and pinout.  If they do then you can just drop it into the design.

    If the opto isolators are not similar you will have to readjust the bias current and decompensate the voltage loop. 

    Regards,