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UCC28634: UCC28634 vs. UCC28631

Part Number: UCC28634
Other Parts Discussed in Thread: UCC28631,

Hi, could someone provide me a list of differences between UCC28634 and UCC28631? Am I right, if there is difference only in Level of UV/OV Detection?

we have already a system with UCC28631. It runs well, but according to IEC62752 we have to comply with cap. 9.7.8.2 which means, that the system has to run below 50Vac/50Hz. Due to Undervoltage detection we fall out in this test.

Ist there any option (tuning), how we can disable this detection?

thank you.

  • Hello Vorisek,

    Thank you for your interest in the UCC2863x family of flyback controllers.
    The family datasheet www.ti.com/.../ucc28631.pdf has a features comparison table on page 5.

    A scan of the datasheet spec table indicates that OV detect and SD fault-clearing thresholds are different between the -631 and -634.
    ACon and ACoff differences are shown in table 6, page 52 of the datasheet.
    Because these levels are detected at the VSENSE input through a resistor divider network (Figure 28, page 29), it may be possible to dynamically adjust the divider ratio (or alter the VSENSE negative current) with an external circuit so that a wider input range is allowable.

    I don't have a specific application circuit for this situation, but it "feels" like something that can be designed (although I'm not sure how simple or complicated it would be). I'll need to confer with some other experts on this, and will get back to you as soon as I can.

    Regards,
    Ulrich
  • Hello Mr. Goerke,

    thank you for your reply. I have enlarged pullup resistor from 3k9 to 4k75. With this was UV Level decreased. So, thank you again for your tip!

    best regards, Radim.