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UCC28750EVM-071: Replace switches with alternative materials made of SiC

yang-lun chien
Prodigy 60 points
Part Number: UCC28750EVM-071
Other Parts Discussed in Thread: UCC28750, UCC27531

Tool/software:

hello
I've referred to the design of UCC28750EVM to make a test samples,
here is the schematic:


Part Q3 is the controller switch, and it's part number is IPP65R190C7FKSA1.
Under this condition, the average efficiency measured is equivalent to the specification of UCC28750EVM.
and then,I tried replacing Q3 with 3 different SiC alternatives:
1、NTHL040N120SC
2、C2M0040120D
3、TW030N120C
but the average efficiency after testing is about 3%~4% lower than the original material.
I would like to ask if there will be any problems if Q3 is directly replaced with alternative materials like this?
Do the related parts around Q3 also need to be changed?
Please help, thank you.

  • 0
    TI__Guru* 86286 points

    Hello,

     

    The UCC28750 was designed to drive Si FETs which have a miller plateau of around 4.5 V and is recommended to drive most Si FETs with a gate drive voltage of around 12 V to fully utilize the FET.  SiC FETs have a higher miller plateau around 7 to 10 V.  It is preferred to drive these SiC FETs with 15 to 18 V to fully utilize the FET.

     

    I believe your issue is that the UCC28750 controller was optimized for Si FETs and SiC.  You should be able to improve the efficiency by driving the FETs with SiC FET drivers in your application.  The following link will bring you to an application note discusses how to drive SiC FETs using the UCC27531 SiC FET driver.

    https://www.ti.com/lit/an/slua770a/slua770a.pdf

     

    Thank you for interest in Texas Instruments (TI) products.  If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

     

    Regards,