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UCC21750: Is it an important issue not to have the Advanced Active Clamping option?

Xabier Albistegui
Prodigy 80 points
Part Number: UCC21750
Other Parts Discussed in Thread: UCC5870-Q1

Hi,

Is it really an important issue not to have the Advanced Active Clamp? I need an efficient protection against IGBT collector-emitter over-voltages and I wanted to know if there is any problem if the UCC21750 does not have this option. 

Thanks

  • +1
    TI__Genius 10652 points

    Xabier,

    In the applications we see UCC217xx in, I have not seen Active Clamp used before for IGBTs. Unless you have a "corner case" usage, I would say it is most likely not needed.

    This feature can be implemented discretely if needed, but unless you are having very large VCE overshoots that 1) are not effectively protected by teh device after SC detection 2) risk damage to the device, I would say it is not needed.

    Regarding discrete implementation, Littelfuse has a short app note that shows how to implement this with their discrete Diodes.

    UCC5870-Q1 has this feature built-in, but this is a super-advanced driver with more than 2x the pin count and SPI.  not even in the same ballpark as UCC21750.

    Xabier Albistegui said:
    I need an efficient protection against IGBT collector-emitter over-voltages

    If you are talking about protecting against VCE overvoltage such as a short-circuit event, and preventing the overshoot that can happen during turn-off in a shortcircuit condition, UCC217xx family has built-in SC detection and safe shutdown features which are intended exactly for this.

    Please see our FAQ which gives comparison between all UCC217xx family

    https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1011093/faq-ucc21710-what-are-the-differences-between-ucc217xx-and-iso5x5x

    SC (shortcircuit) protection detects when IGBT VCE voltage is too high (exits saturation region), and then turns off the device. In UCC217xx, there is a safe shutdown procedure which turns off the gate gradually to reduce overshoot and prevent damage. So in this sense, there is already a form of VCE protectino built-in

    UCC217xx family ALL has softtuurn off / safe shutdown feature which reduce VCE overshoot when turning off the device after a short-circuit condition and are highly effective.

    Please let me know if this answers all your questions by pressing the Resolved button. If you have additional questions, please let me know!

    best

    Dimitri