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LM3481-FLYBACKEVM: OVP measurement.

Part Number: LM3481-FLYBACKEVM
Other Parts Discussed in Thread: LM3481, TL431

Hi Team,

LM3481 have output OVP function.

Could you let me know how to measure the feature for OVP using flybackEVM?

I attempt to short the LTV-817S pin1/2, output voltage clamp on 9V I think it doesn't measure like this? Do you have any suggestion?

Regards,

Roy   

  • Hi Roy,

    The OVP is built in at the FB pin and it is usually grounded for isolated flyback.  Shorting the pin1 and 2 of the opto does not help.   You should consider to add a ~ 6.5V zener from the output rail to the TL431 ref pin, and it will drive the opto strongly, consequently stops the switching and achieve OVP.

    Thanks,

    Youhao Xi, Applications Engineering