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UCC21710: Difference between working voltage and DC operating voltage

Arun Ashok
Prodigy 90 points
Part Number: UCC21710
Other Parts Discussed in Thread: UCC21750

Hi Apps team,

I was going through the datasheet of UCC21710/21750 and had some doubts:

1) On the first page of both data sheets a working voltage of 1500V is specified, but it also states that " it supports SiC MOSFETs and IGBTs upto 2121V DC operating voltage".

    What is the difference between these two values. If I am having an application with a DC link voltage of 1500V, are these drivers suitable for it?

2) What is the difference between these two drivers - UCC21710 and UCC21750 - can they be used interchangeably?

3) Can I get a faster SC response by eliminating the Cdesat Cap? 

Thank you,

Arun

  • 0
    TI__Expert 6730 points

    Hi Arun, 

    1. Yes, you can use a DC voltage of 1500V. If you look at this page of the datasheet you can see that the 1500V is the RMS voltage of the sine wave of the maximum isolation working voltage. The maximum isolating DC voltage is 2121V. 

    2. Please see this link about the difference between UCC21710 and UCC21750. The main difference is the OC pin vs. DESAT pin, and should be designed differently. 

    3. Are you talking about the blanking capacitor Cblk in the figure below? We would not recommend eliminating it as Cblk help with noise immunity on the DESAT pin. 

    Thanks, 

    Vivian

  • 0 in reply to Vivian Qi
    Prodigy 90 points

    Hi Vivian,

    Do you have any links for the design mentioned in 2) ?

    For 3), after a blanking time of 200ns, what is the minimum total desat detection + soft turn off than can be achieved by the gate driver? Can you share any design guidelines for that? 

    Thank you,

    Arun

  • +1 in reply to Arun Ashok
    TI__Expert 6730 points

    Hi Arun, 

    The 21710 datasheet and 21750 datasheet has schematics for the DESAT and OC design. Additionally, you can check out this calculator that calculates the detection threshold, blanking time, etc. The calculator can also calculate the soft turn off time. 

    Be aware that besides the leading edge blanking time, UCC21750 also has DESAT deglitch time (150ns) and DESAT to OUTL propagation delay (200ns) that all should be counted towards the total turnoff time. UCC21710 does not have the leading edge blanking time, but has OC deglitch time (120ns) and OC to OUTL propagation delay (270ns). All specified in the datasheet. 

    If my answers help you, please press the green button. 

    Thanks, 

    Vivian