TL431LI: Getting lower output voltage when replacing AZ431 with TL431LI in flyback

Hi team,

I am supporting my customer to replace AZ431AN-ATRE1 with TL431LIAIDBZR. According to our knowledge this device should be drop in compatible, but after changing the device we are only getting 6.7V output rather than 12V output on the flyback.

Attaching schematics as below. Any modificatioB need to be done for TL431?

Regards,

Brian