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UCC27282: High-side to low-side gate driver request

Jonathan Geronga
Expert 7930 points
Part Number: UCC27282
Other Parts Discussed in Thread: UCC5350

Hi Team,

I am posting this on behalf of the customer and I use UCC27282 as TI part because of I that this is the nearest possible product I found so far but I hope someone can recommend a better TI part if we have this:

The customer is looking for a gate driver, high side to low side (instead of low- to high-side). The input of the gate-driver is referenced to 150 VDC, the output is referenced to 0V.

Other information I got from the customer:

"The topology is an LLC-converter for railway-application and it's going to be used on various projects.
For a high power application, we want to implement a LLC full-bridge on the primary-side (normally only half-bridge). Therefore, the high-side driver of the LLC-controller has to drive a high-side FET (directly with LLC-controller integrated high-side gate driver) AND a low side FET at the same time. To drive the low-side FET with the same timing as the high-side FET, we need a high-to-low-side gate driver. The input-voltage of the LLC-converter is 110 - 150 VDC, therefore, the high side driver of the LLC-controller is referenced to this voltage, while the low-side FET is referenced to 0 VDC."




Here's the customer circuit diagram.

Please let me know if you need more information.

Thanks!

Jonathan

  • 0
    TI__Mastermind 21965 points

    Hello Jonathan,

    Thank you for supporting TI drivers. For the app you are supporting, a high voltage control to low voltage gate drive, I think you need one of the isolated drivers which can level shift in either positive or negative polarities. The HB drivers, such as UCC27282, are targeted for low voltage, ground referenced control and the need for a high side floating gate drive, as well as the low side drive.

    I will forward this post to the experts on the isolated drivers, to help pick the best device.

    Regards,

  • 0
    TI__Genius 10652 points

    Hi, Jonathan

    That part you mentioned would not work in that configuaration without level shifter. Used like this, the HV gate drive bias signal HVG to the input of the additional gate driverwould be referenced to ground, which would destroy UCC27282 pretty fast.

    We don't typically see the daisy chaining of drivers like this, but if they are set on it it, I would recommend to use an isolated gate driver instead, with input side ground referenced to FET1 source instead of ground. This way no external level shifter would be required, as the input and output sides of the driver would then be isolated and input side's ground could be referenced to the high-side FET source.

    Because the part you mentioned source/sink 4/6A respectively, I would recommend to take a look at UCC5350 , specifically UCC5350SBD, a 5A/5A part with 8V UVLO that can handle the 12V FET source-referenced input. 

    http://www.ti.com/product/UCC5350

    Another option they can consider is to not use any bootstrap in their LLC controller HVG output, to get 12V referenced to ground. Then to use 2 dual-channel or 4 single channel gate driver, bootstrapping those high side drivers if that is a possibility. In this case, they could also have the option to choose a pair or 4 non-isolated gate drivers.

    I think that their solution to just tack on a gate driver like this is not the best solution if it can be avoided.

    Best

    Dimitri

  • 0 in reply to dimitri james
    TI__Expert 7930 points

    Hi Richard and Dimitri,

    Thank you very much for your kind support.
    Let me share this with the customer and will let you know if there's any question.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Geronga
    TI__Genius 10652 points

    For sure, Jonathan.

    If possible, could you ask them which LLC controller they plan on using?
    Best

    DImitri

  • 0 in reply to dimitri james
    Prodigy 160 points

    Hi Dimitri

    Thank you for your support!

    The isolated driver you suggested is exactly what we were looking for.

    We will implement the circuit with this driver.

    Best regards

    Christian

  • 0 in reply to Christian Carlen
    TI__Genius 10652 points

    Christian, Great to hear!

    Best

    Dimitri